diff --git a/node_modules/dialog-polyfill/suite.js b/node_modules/dialog-polyfill/suite.js
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+/*
+ * Copyright 2015 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+
+void function() {
+
+  /**
+   * Asserts that the displayed dialog is in the center of the screen.
+   *
+   * @param {HTMLDialogElement?} opt_dialog to check, or test default
+   */
+  function checkDialogCenter(opt_dialog) {
+    var d = opt_dialog || dialog;
+    var expectedTop = (window.innerHeight - d.offsetHeight) / 2;
+    var expectedLeft = (window.innerWidth - d.offsetWidth) / 2;
+    var rect = d.getBoundingClientRect();
+    assert.closeTo(rect.top, expectedTop, 1, 'top should be nearby');
+    assert.closeTo(rect.left, expectedLeft, 1, 'left should be nearby');
+  }
+
+  /**
+   * Creates a fake KeyboardEvent.
+   *
+   * @param {number} keyCode to press
+   * @param {string?} opt_type to use, default keydown
+   * @return {!Event} event
+   */
+  function createKeyboardEvent(keyCode, opt_type) {
+    var ev = document.createEvent('Events');
+    ev.initEvent(opt_type || 'keydown', true, true);
+    ev.keyCode = keyCode;
+    ev.which = keyCode;
+    return ev;
+  }
+
+  /**
+   * Cleans up any passed DOM elements.
+   *
+   * @param {!Element} el to clean up
+   * @return {!Element} the same element, for chaining
+   */
+  var cleanup = (function() {
+    var e = [];
+    teardown(function() {
+      e.forEach(function(el) {
+        try {
+          el.close();  // try to close dialogs
+        } catch (e) {}
+        el.parentElement && el.parentElement.removeChild(el);
+      });
+      e = [];
+    });
+
+    return function(el) {
+      e.push(el);
+      return el;
+    };
+  })();
+
+  /**
+   * Creates a dialog for testing that will be cleaned up later.
+   *
+   * @param {string?} opt_content to be used as innerHTML
+   */
+  function createDialog(opt_content) {
+    var dialog = document.createElement('dialog');
+    dialog.innerHTML = opt_content || 'Dialog #' + (cleanup.length);
+    document.body.appendChild(dialog);
+    if (window.location.search == '?force') {
+      dialogPolyfill.forceRegisterDialog(dialog);
+    } else {
+      dialogPolyfill.registerDialog(dialog);
+    }
+    return cleanup(dialog);
+  }
+
+  var dialog;  // global dialog for all tests
+  setup(function() {
+    dialog = createDialog('Default Dialog');
+  });
+
+  suite('basic', function() {
+    test('show and close', function() {
+      assert.isFalse(dialog.hasAttribute('open'));
+      dialog.show();
+      assert.isTrue(dialog.hasAttribute('open'));
+      assert.isTrue(dialog.open);
+
+      var returnValue = 1234;
+      dialog.close(returnValue);
+      assert.isFalse(dialog.hasAttribute('open'));
+      assert.equal(dialog.returnValue, returnValue);
+
+      dialog.show();
+      dialog.close();
+      assert.isFalse(dialog.open);
+      assert.equal(dialog.returnValue, returnValue);
+    });
+    test('open property', function() {
+      assert.isFalse(dialog.hasAttribute('open'));
+      dialog.show();
+      assert.isTrue(dialog.hasAttribute('open'));
+      assert.isTrue(dialog.open);
+
+      dialog.open = false;
+      assert.isFalse(dialog.open);
+      assert.isFalse(dialog.hasAttribute('open'),
+          'open property should clear attribute');
+      assert.throws(dialog.close);
+
+      var overlay = document.querySelector('._dialog_overlay');
+      assert.isNull(overlay);
+    });
+    test('show/showModal interaction', function() {
+      assert.isFalse(dialog.hasAttribute('open'));
+      dialog.show();
+
+      // If the native dialog is being tested, show/showModal are not already
+      // bound, so wrap them in helper methods for throws/doesNotThrow.
+      var show = function() { dialog.show(); };
+      var showModal = function() { dialog.showModal(); };
+
+      assert.doesNotThrow(show);
+      assert.throws(showModal);
+
+      dialog.open = false;
+      assert.doesNotThrow(showModal);
+      assert.doesNotThrow(show);  // show after showModal does nothing
+      assert.throws(showModal);
+      // TODO: check dialog is still modal
+
+      assert.isTrue(dialog.open);
+    });
+    test('setAttribute reflects property', function() {
+      dialog.setAttribute('open', '');
+      assert.isTrue(dialog.open, 'attribute opens dialog');
+    });
+    test('changing open to dummy value is ignored', function() {
+      dialog.showModal();
+
+      dialog.setAttribute('open', 'dummy, ignored');
+      assert.isTrue(dialog.open, 'dialog open with dummy open value');
+
+      var overlay = document.querySelector('._dialog_overlay');
+      assert(overlay, 'dialog is still modal');
+    });
+    test('show/showModal outside document', function() {
+      dialog.open = false;
+      dialog.parentNode.removeChild(dialog);
+
+      assert.throws(function() { dialog.showModal(); });
+
+      assert.doesNotThrow(function() { dialog.show(); });
+      assert.isTrue(dialog.open, 'can open non-modal outside document');
+      assert.isFalse(document.body.contains(dialog));
+    });
+    test('has a11y property', function() {
+      assert.equal(dialog.getAttribute('role'), 'dialog', 'role should be dialog');
+    });
+  });
+
+  suite('DOM', function() {
+    setup(function(done) {
+      // DOM tests wait for modal to settle, so MutationOberver doesn't coalesce attr changes
+      dialog.showModal();
+      window.setTimeout(done, 0);
+    });
+    test('DOM direct removal', function(done) {
+      assert.isTrue(dialog.open);
+      assert.isNotNull(document.querySelector('.backdrop'));
+
+      var parentNode = dialog.parentNode;
+      parentNode.removeChild(dialog);
+
+      // DOMNodeRemoved defers its task a frame (since it occurs before removal, not after). This
+      // doesn't effect MutationObserver, just delays the test a frame.
+      window.setTimeout(function() {
+        assert.isNull(document.querySelector('.backdrop'), 'dialog removal should clear modal');
+
+        assert.isTrue(dialog.open, 'removed dialog should still be open');
+        parentNode.appendChild(dialog);
+
+        assert.isTrue(dialog.open, 're-added dialog should still be open');
+        assert.isNull(document.querySelector('.backdrop'), 're-add dialog should not be modal');
+
+        done();
+      }, 0);
+    });
+    test('DOM removal inside other element', function(done) {
+      var div = cleanup(document.createElement('div'));
+      document.body.appendChild(div);
+      div.appendChild(dialog);
+
+      document.body.removeChild(div);
+
+      window.setTimeout(function() {
+        assert.isNull(document.querySelector('.backdrop'), 'dialog removal should clear modal');
+        assert.isTrue(dialog.open, 'removed dialog should still be open');
+        done();
+      }, 0);
+    });
+    test('DOM instant remove/add', function(done) {
+      var div = cleanup(document.createElement('div'));
+      document.body.appendChild(div);
+      dialog.parentNode.removeChild(dialog);
+      div.appendChild(dialog);
+
+      window.setTimeout(function() {
+        assert.isNull(document.querySelector('.backdrop'), 'backdrop should disappear');
+        assert.isTrue(dialog.open);
+        done();
+      }, 0);
+    });
+  });
+
+  suite('position', function() {
+    test('non-modal is not centered', function() {
+      var el = cleanup(document.createElement('div'));
+      dialog.parentNode.insertBefore(el, dialog);
+      var testRect = el.getBoundingClientRect();
+
+      dialog.show();
+      var rect = dialog.getBoundingClientRect();
+
+      assert.equal(rect.top, testRect.top, 'dialog should not be centered');
+    });
+    test('default modal centering', function() {
+      dialog.showModal();
+      checkDialogCenter();
+      assert.ok(dialog.style.top, 'expected top to be set');
+      dialog.close();
+      assert.notOk(dialog.style.top, 'expected top to be cleared');
+    });
+    test('modal respects static position', function() {
+      dialog.style.top = '10px';
+      dialog.showModal();
+
+      var rect = dialog.getBoundingClientRect();
+      assert.equal(rect.top, 10);
+    });
+    test('modal recentering', function() {
+      var pX = document.body.scrollLeft;
+      var pY = document.body.scrollTop;
+      var big = cleanup(document.createElement('div'));
+      big.style.height = '200vh';  // 2x view height
+      document.body.appendChild(big);
+
+      try {
+        var scrollValue = 200;  // don't use incredibly large values
+        dialog.showModal();
+        dialog.close();
+
+        window.scrollTo(0, scrollValue);
+        dialog.showModal();
+        checkDialogCenter();  // must be centered, even after scroll
+        var rectAtScroll = dialog.getBoundingClientRect();
+
+        // after scroll, we aren't recentered, check offset
+        window.scrollTo(0, 0);
+        var rect = dialog.getBoundingClientRect();
+        assert.closeTo(rectAtScroll.top + scrollValue, rect.top, 1);
+      } finally {
+        window.scrollTo(pX, pY);
+      }
+    });
+    test('clamped to top of page', function() {
+      var big = cleanup(document.createElement('div'));
+      big.style.height = '200vh';  // 2x view height
+      document.body.appendChild(big);
+      document.documentElement.scrollTop = document.documentElement.scrollHeight / 2;
+
+      dialog.style.height = document.documentElement.scrollHeight + 200 + 'px';
+      dialog.showModal();
+
+      var visibleRect = dialog.getBoundingClientRect();
+      assert.equal(visibleRect.top, 0, 'large dialog should be visible at top of page');
+
+      var style = window.getComputedStyle(dialog);
+      assert.equal(style.top, document.documentElement.scrollTop + 'px',
+          'large dialog should be absolutely positioned at scroll top');
+    });
+  });
+
+  suite('backdrop', function() {
+    test('backdrop div on modal', function() {
+      dialog.showModal();
+      var foundBackdrop = document.querySelector('.backdrop');
+      assert.isNotNull(foundBackdrop);
+
+      var sibling = dialog.nextElementSibling;
+      assert.strictEqual(foundBackdrop, sibling);
+    });
+    test('no backdrop on non-modal', function() {
+      dialog.show();
+      assert.isNull(document.querySelector('.backdrop'));
+      dialog.close();
+    });
+    test('backdrop click appears as dialog', function() {
+      dialog.showModal();
+      var backdrop = dialog.nextElementSibling;
+
+      var clickFired = 0;
+      var helper = function(ev) {
+        assert.equal(ev.target, dialog);
+        ++clickFired;
+      };
+
+      dialog.addEventListener('click', helper)
+      backdrop.click();
+      assert.equal(clickFired, 1);
+    });
+    test('backdrop click focuses dialog', function() {
+      dialog.showModal();
+      dialog.tabIndex = 0;
+
+      var input = document.createElement('input');
+      input.type = 'text';
+      dialog.appendChild(input);
+
+      // TODO: It would be nice to check `input` instead here, but there's no more reliable ways
+      // to emulate a browser tab event (Firefox, Chrome etc have made it a security violation).
+
+      var backdrop = dialog.nextElementSibling;
+      backdrop.click();
+      assert.equal(document.activeElement, dialog);
+    });
+  });
+
+  suite('form focus', function() {
+    test('non-modal inside modal is focusable', function() {
+      var sub = createDialog();
+      dialog.appendChild(sub);
+
+      var input = document.createElement('input');
+      input.type = 'text';
+      sub.appendChild(input);
+
+      dialog.showModal();
+      sub.show();
+
+      input.focus();
+      assert.equal(input, document.activeElement);
+    });
+    test('clear focus when nothing focusable in modal', function() {
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      document.body.appendChild(input);
+      input.focus();
+
+      var previous = document.activeElement;
+      dialog.showModal();
+      assert.notEqual(previous, document.activeElement);
+    });
+    test('default focus on modal', function() {
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      dialog.appendChild(input);
+
+      var anotherInput = cleanup(document.createElement('input'));
+      anotherInput.type = 'text';
+      dialog.appendChild(anotherInput);
+
+      dialog.showModal();
+      assert.equal(document.activeElement, input);
+    });
+    test('default focus on non-modal', function() {
+      var div = cleanup(document.createElement('div'));
+      div.tabIndex = 4;
+      dialog.appendChild(div);
+
+      dialog.show();
+      assert.equal(document.activeElement, div);
+    });
+    test('autofocus element chosen', function() {
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      dialog.appendChild(input);
+
+      var inputAF = cleanup(document.createElement('input'));
+      inputAF.type = 'text';
+      inputAF.autofocus = true;
+      dialog.appendChild(inputAF);
+
+      dialog.showModal();
+      assert.equal(document.activeElement, inputAF);
+    });
+    test('child modal dialog', function() {
+      dialog.showModal();
+
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      dialog.appendChild(input);
+      input.focus();
+      assert.equal(document.activeElement, input);
+
+      // NOTE: This is a single sub-test, but all the above tests could be run
+      // again in a sub-context (i.e., dialog within dialog).
+      var child = createDialog();
+      child.showModal();
+      assert.notEqual(document.activeElement, input,
+          'additional modal dialog should clear parent focus');
+
+      child.close();
+      assert.notEqual(document.activeElement, input,
+          'parent focus should not be restored');
+    });
+    test('don\'t scroll anything into focus', function() {
+      // https://github.com/GoogleChrome/dialog-polyfill/issues/119
+
+      var div = cleanup(document.createElement('div'));
+      document.body.appendChild(div);
+
+      var inner = document.createElement('div');
+      inner.style.height = '10000px';
+      div.appendChild(inner);
+
+      div.appendChild(dialog);
+
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      dialog.appendChild(input);
+
+      var prev = document.documentElement.scrollTop;
+      dialog.showModal();
+      assert.equal(document.documentElement.scrollTop, prev);
+    });
+  });
+
+  suite('top layer / inert', function() {
+    test('background focus allowed on non-modal', function() {
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      document.body.appendChild(input);
+      input.focus();
+
+      dialog.show();
+      assert.notEqual(document.activeElement, input,
+        'non-modal dialog should clear focus, even with no dialog content');
+
+      document.body.focus();
+      input.focus();
+      assert.equal(document.activeElement, input,
+          'non-modal should allow background focus');
+    });
+    test('modal disallows background focus', function() {
+      var input = cleanup(document.createElement('input'));
+      input.type = 'text';
+      document.body.appendChild(input);
+
+      dialog.showModal();
+      input.focus();
+
+      if (!document.hasFocus()) {
+        // Browsers won't trigger a focus event if they're not in the
+        // foreground, so we can't intercept it. However, they'll fire one when
+        // restored, before a user can get to any incorrectly focused element.
+        console.warn('background focus test requires document focus');
+        document.documentElement.focus();
+      }
+      assert.notEqual(document.activeElement, input,
+          'modal should disallow background focus');
+    });
+    test('overlay is a sibling of topmost dialog', function() {
+      var stacking = cleanup(document.createElement('div'));
+      stacking.style.opacity = 0.8;  // creates stacking context
+      document.body.appendChild(stacking);
+      stacking.appendChild(dialog);
+      dialog.showModal();
+
+      var overlay = document.querySelector('._dialog_overlay');
+      assert.isNotNull(overlay);
+      assert.equal(overlay.parentNode, dialog.parentNode);
+    });
+    test('overlay is between topmost and remaining dialogs', function() {
+      dialog.showModal();
+
+      var other = cleanup(createDialog());
+      document.body.appendChild(other);
+      other.showModal();
+
+      var overlay = document.querySelector('._dialog_overlay');
+      assert.isNotNull(overlay);
+      assert.equal(overlay.parentNode, other.parentNode);
+
+      assert.isAbove(+other.style.zIndex, +overlay.style.zIndex, 'top-most dialog above overlay');
+      assert.isAbove(+overlay.style.zIndex, +dialog.style.zIndex, 'overlay above other dialogs');
+    });
+  });
+
+  suite('events', function() {
+    test('close event', function() {
+      var closeFired = 0;
+      dialog.addEventListener('close', function() {
+        ++closeFired;
+      });
+
+      dialog.show();
+      assert.equal(closeFired, 0);
+
+      dialog.close();
+      assert.equal(closeFired, 1);
+
+      assert.throws(dialog.close);  // can't close already closed dialog
+      assert.equal(closeFired, 1);
+
+      dialog.showModal();
+      dialog.close();
+      assert.equal(closeFired, 2);
+    });
+    test('cancel event', function() {
+      dialog.showModal();
+      dialog.dispatchEvent(createKeyboardEvent(27));
+      assert.isFalse(dialog.open, 'esc should close modal');
+
+      var cancelFired = 0;
+      dialog.addEventListener('cancel', function() {
+        ++cancelFired;
+      });
+      dialog.showModal();
+      dialog.dispatchEvent(createKeyboardEvent(27));
+      assert.equal(cancelFired, 1, 'expected cancel to be fired');
+      assert.isFalse(dialog.open), 'esc should close modal again';
+
+      // Sanity-check that non-modals aren't effected.
+      dialog.show();
+      dialog.dispatchEvent(createKeyboardEvent(27));
+      assert.isTrue(dialog.open, 'esc should only close modal dialog');
+      assert.equal(cancelFired, 1);
+    });
+    test('overlay click is prevented', function() {
+      dialog.showModal();
+
+      var overlay = document.querySelector('._dialog_overlay');
+      assert.isNotNull(overlay);
+
+      var helper = function(ev) {
+        throw Error('body should not be clicked');
+      };
+      try {
+        document.body.addEventListener('click', helper);
+        overlay.click();
+      } finally {
+        document.body.removeEventListener('click', helper);
+      }
+    });
+  });
+
+  suite('form', function() {
+    test('method attribute is translated to property', function() {
+      var form = document.createElement('form');
+      form.method = 'dialog';
+      assert.equal(form.method, 'dialog');
+
+      form.method = 'PoSt';
+      assert.equal(form.method, 'post');
+      assert.equal(form.getAttribute('method'), 'PoSt');
+    });
+    test('dialog method input', function() {
+      var value = 'ExpectedValue' + Math.random();
+
+      var form = document.createElement('form');
+      try {
+        form.method = 'dialog';
+      } catch (e) {
+        // Setting the method directly throws an exception in <=IE9.
+        form.setAttribute('method', 'dialog');
+      }
+      dialog.appendChild(form);
+
+      var input = document.createElement('input');
+      input.type = 'submit';
+      input.value = value;
+      form.appendChild(input);
+
+      var closeCount = 0;
+      dialog.addEventListener('close', function() {
+        ++closeCount;
+      });
+
+      dialog.show();
+      input.focus();  // emulate user focus action
+      input.click();
+
+      assert.isFalse(dialog.open);
+      assert.equal(dialog.returnValue, value);
+      assert.equal(closeCount, 1);
+    });
+    test('dialog with button preventDefault does not trigger submit', function() {
+      var form = document.createElement('form');
+      form.setAttribute('method', 'dialog');
+      dialog.appendChild(form);
+
+      var button = document.createElement('button');
+      button.value = 'does not matter';
+      form.appendChild(button);
+      button.addEventListener('click', function(ev) {
+        ev.preventDefault();
+      });
+
+      dialog.showModal();
+      button.click();
+
+      assert.isTrue(dialog.open, 'dialog should remain open');
+      assert.equal(dialog.returnValue, '');
+    });
+    test('dialog programmatic submit does not change returnValue', function() {
+      var form = document.createElement('form');
+      form.setAttribute('method', 'dialog');
+
+      dialog.returnValue = 'manually set';  // set before appending
+      dialog.appendChild(form);
+
+      dialog.showModal();
+      form.submit();
+      assert.isFalse(dialog.open);
+
+      assert.equal(dialog.returnValue, 'manually set', 'returnValue should not change');
+    });
+    test('dialog method button', function() {
+      var value = 'ExpectedValue' + Math.random();
+
+      var form = document.createElement('form');
+      form.setAttribute('method', 'dialog');
+      dialog.appendChild(form);
+
+      var button = document.createElement('button');
+      button.value = value;
+      form.appendChild(button);
+
+      dialog.showModal();
+      button.focus();  // emulate user focus action
+      button.click();
+
+      assert.isFalse(dialog.open);
+      assert.equal(dialog.returnValue, value);
+
+      // Clear button value, confirm textContent is not used as value.
+      button.value = 'blah blah';
+      button.removeAttribute('value');
+      button.textContent = value;
+      dialog.show();
+      button.focus();  // emulate user focus action
+      button.click();
+
+      assert.equal(dialog.returnValue, button.value,
+          'don\'t take button textContent as value');
+    });
+    test('boring form inside dialog', function() {
+      var form = document.createElement('form');
+      dialog.appendChild(form);  // don't specify method
+      form.addEventListener('submit', function(ev) {
+        ev.preventDefault();
+      });
+
+      var button = document.createElement('button');
+      button.value = 'Moot';
+      form.appendChild(button);
+
+      dialog.showModal();
+      button.focus();  // emulate user focus action
+      button.click();
+
+      assert.isTrue(dialog.open, 'non-dialog form should not close dialog')
+      assert(!dialog.returnValue);
+    });
+    test('type="image" submitter', function() {
+      var form = document.createElement('form');
+      form.setAttribute('method', 'dialog');
+      dialog.appendChild(form);
+      dialog.show();
+
+      var image = document.createElement('input');
+      image.type = 'image';
+      image.src = 'data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==';
+      image.setAttribute('value', 'image should not accept value');
+      form.appendChild(image);
+      image.click();
+
+      assert.notEqual(image.getAttribute('value'), dialog.returnValue);
+      assert.equal(dialog.returnValue, '0,0');
+    });
+    test('form submitter across dialogs', function() {
+      var form1 = document.createElement('form');
+      form1.setAttribute('method', 'dialog');
+      dialog.appendChild(form1);
+
+      var button1 = document.createElement('button');
+      button1.value = 'from form1: first value';
+      form1.appendChild(button1);
+      dialog.showModal();
+
+      var dialog2 = createDialog();
+      dialog2.returnValue = 'dialog2 default close value';
+      var form2 = document.createElement('form');
+      form2.setAttribute('method', 'dialog');
+      dialog2.appendChild(form2);
+      dialog2.showModal();
+
+      button1.click();
+      assert.isFalse(dialog.open);
+
+      // nb. this never fires 'submit' so the .returnValue can't be wrong: is there another way
+      // to submit a form that doesn't involve a click (enter implicitly 'clicks') or submit?
+      form2.submit();
+      assert.isFalse(dialog2.open);
+
+      assert.equal(dialog2.returnValue, 'dialog2 default close value',
+          'second dialog shouldn\'t reuse formSubmitter');
+    });
+  });
+
+  suite('order', function() {
+    test('non-modal unchanged', function() {
+      var one = createDialog();
+      var two = createDialog();
+
+      one.style.zIndex = 100;
+      two.style.zIndex = 200;
+      one.show();
+      two.show();
+
+      assert.equal(window.getComputedStyle(one).zIndex, 100);
+      assert.equal(window.getComputedStyle(two).zIndex, 200);
+
+      two.close();
+      assert.equal(window.getComputedStyle(two).zIndex, 200);
+    });
+    test('modal stacking order', function() {
+      dialog.showModal();
+
+      // Create incorrectly-named dialogs: front has a lower z-index, and back
+      // has a higher z-index.
+      var front = createDialog();
+      var back = createDialog();
+      front.style.zIndex = 100;
+      back.style.zIndex = 200;
+
+      // Show back first, then front. Thus we expect back to be behind front.
+      back.showModal();
+      front.showModal();
+
+      var zf = +window.getComputedStyle(front).zIndex;
+      var zb = +window.getComputedStyle(back).zIndex;
+      assert.isAbove(zf, zb, 'showModal order dictates z-index');
+
+      var backBackdrop = back.nextElementSibling;
+      var zbb = +window.getComputedStyle(backBackdrop).zIndex;
+      assert.equal(backBackdrop.className, 'backdrop');
+      assert.isBelow(zbb, zb, 'backdrop below dialog');
+
+      var frontBackdrop = front.nextElementSibling;
+      var zfb = +window.getComputedStyle(frontBackdrop).zIndex
+      assert.equal(frontBackdrop.className, 'backdrop');
+      assert.isBelow(zfb, zf,' backdrop below dialog');
+
+      assert.isAbove(zfb, zb, 'front backdrop is above back dialog');
+
+      front.close();
+      assert.notOk(front.style.zIndex, 'modal close should clear zindex');
+    });
+  });
+
+  suite('press tab key', function() {
+    test('tab key', function() {
+      var dialog = createDialog();
+      dialog.showModal();
+
+      document.documentElement.dispatchEvent(createKeyboardEvent(9));
+
+      var ev = document.createEvent('Events');
+      ev.initEvent('focus', true, true);
+      document.documentElement.dispatchEvent(ev);
+
+      dialog.close();
+    });
+  });
+}();