Add test data for spaceport benchmark.

chrome/test/data/third_party/spaceport/js/util/ensureCallback.js

+define([ ], function () {
+    return function ensureCallback(callback) {
+        if (typeof callback !== 'function') {
+            return function (err) {
+                if (err) {
+                    console.error(err);
+                }
+            };
+        }
+
+        var called = false;
+        return function () {
+            if (called) {
+                // Disallow calling multiple times
+                return;
+            }
+
+            called = true;
+            var args = arguments;
+
+            setTimeout(function () {
+                // Ensure async
+                callback.apply(null, args);
+            }, 0);
+        };
+    };
+});