Add experiments link to the options page

This link points to the experiments page, and is only shown in
non-release versions of the extension.

Change-Id: I09db9e6ded29be7f6f03f97378cd9311f88d40d3
diff --git a/src/options/options_common.js b/src/options/options_common.js
index 10fee88..098a632 100644
--- a/src/options/options_common.js
+++ b/src/options/options_common.js
@@ -77,6 +77,14 @@
 window.addEventListener('load', function() {
   i18n();
 
+  if (window.CONTEXT == 'options' && !isReleaseVersion()) {
+    var experimentsLink = document.querySelector('.experiments-link');
+    experimentsLink.removeAttribute('hidden');
+    experimentsLink.addEventListener('click', _ => chrome.tabs.create({
+      url: chrome.runtime.getURL('options/experiments.html'),
+    }));
+  }
+
   chrome.storage.sync.get(null, function(items) {
     items = cleanUpOptions(items, false);