Add a sketch of a test_perf script

sky/benchmarks/resources/runner.sky

 <script>
 function PerfRunner(options) {
   this.unit_ = options.unit || "ms";
   this.iterationsRemaining_ = options.iterations || 10;
   this.results_ = [];
   this.setup_ = options.setup;
+  this.logLines_ = [];
 }
 
 PerfRunner.prototype.log = function(line) {
-  console.log(line);
+  this.logLines_.push(line);
 };
 
 PerfRunner.prototype.recordResult = function(result) {
-  console.log(result);
   this.results_.push(result);
 };
 
 PerfRunner.prototype.runAsync = function(test) {
   var self = this;
   window.setTimeout(function() {
     if (self.setup_) {
       var setup = self.setup_;
       setup();
     }
@@ skipping 50 matching lines @@
     this.log("values " + stats.values.join(", ") + " " + stats.unit);
   this.log("avg " + stats.mean + " " + stats.unit);
   this.log("median " + stats.median + " " + stats.unit);
   this.log("stdev " + stats.stdev + " " + stats.unit);
   this.log("min " + stats.min + " " + stats.unit);
   this.log("max " + stats.max + " " + stats.unit);
 };
 
 PerfRunner.prototype.finish = function () {
   this.logStatistics("Time:");
+  internals.notifyTestComplete(this.logLines_.join('\n'));
 }
 
 module.exports = PerfRunner;
 </script>