Import web-platform-tests/webstorage

LayoutTests/imported/web-platform-tests/webstorage/eventTestHarness.js

+iframe = document.createElement("IFRAME");
+iframe.src = "about:blank";
+document.body.appendChild(iframe);
+iframe.contentWindow.document.body.textContent = "Nothing to see here.";
+
+storageEventList = new Array();
+iframe.contentWindow.addEventListener("storage", function(e) {
+    window.parent.storageEventList.push(e);
+});
+
+function runAfterNStorageEvents(callback, expectedNumEvents)
+{
+    countStorageEvents(callback, expectedNumEvents, 0)
+}
+
+function countStorageEvents(callback, expectedNumEvents, times)
+{
+    function onTimeout()
+    {
+        var currentCount = storageEventList.length;
+        if (currentCount == expectedNumEvents) {
+            callback();
+        } else if (currentCount > expectedNumEvents) {
+            msg = "got at least " + currentCount + ", expected only " + expectedNumEvents + " events";
+            callback(msg);
+        } else if (times > 50) {
+            msg = "Timeout: only got " + currentCount + ", expected " + expectedNumEvents + " events";
+            callback(msg);
+        } else {
+            countStorageEvents(callback, expectedNumEvents, times+1);
+        }
+    }
+    setTimeout(onTimeout, 20);
+}
+
+function testStorages(testCallback)
+{
+    testCallback("sessionStorage");
+    var hit = false;
+    add_result_callback(function() {
+        if (!hit) {
+            hit = true;
+            testCallback("localStorage");
+        }
+    });
+}