Add test data for spaceport benchmark.

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

+define([ 'util/ensureCallback' ], function (ensureCallback) {
+    // Benchmarks fn until maxTime ms has passed.  Returns approximate number
+    // of operations performed in that time ('score').
+    function benchAsync(maxTime, fn, callback) {
+        if (typeof fn !== 'function') {
+            throw new TypeError('Argument must be a function');
+        }
+
+        var operationCount = 0;
+        var startTime;
+
+        function next() {
+            fn(operationCount, function () {
+                ++operationCount;
+
+                var endTime = Date.now();
+                if (endTime - startTime >= maxTime) {
+                    var score = operationCount / (endTime - startTime) * maxTime;
+                    return callback(null, score);
+                } else {
+                    return next();
+                }
+            });
+        }
+
+        setTimeout(function () {
+            startTime = Date.now();
+            next();
+        }, 0);
+    }
+
+    return benchAsync;
+});