update-w3c-deps import using blink cc6d84edb87e89c363ab48dac8a983213b9dc02c:

third_party/WebKit/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);
 });
 
@@ skipping 15 matching lines @@
         } else if (times > 50) {
             msg = "Timeout: only got " + currentCount + ", expected " + expectedNumEvents + " events";
             callback(msg);
         } else {
             countStorageEvents(callback, expectedNumEvents, times+1);
         }
     }
     setTimeout(onTimeout, 20);
 }
 
+function clearStorage(storageName, callback)
+{
+    if (window[storageName].length === 0) {
+        storageEventList = [];
+        setTimeout(callback, 0);
+    } else {
+        window[storageName].clear();
+        runAfterNStorageEvents(function() {
+            storageEventList = [];
+            callback();
+        }, 1);
+    }
+}
+
 function testStorages(testCallback)
 {
     testCallback("sessionStorage");
     var hit = false;
     add_result_callback(function() {
         if (!hit) {
             hit = true;
             testCallback("localStorage");
         }
     });
 }