Add browser controller and allow it to be used under a flag.

pkg/unittest/lib/test_controller.js

Index: pkg/unittest/lib/test_controller.js
===================================================================
--- pkg/unittest/lib/test_controller.js	(revision 22503)
+++ pkg/unittest/lib/test_controller.js	(working copy)
@@ -33,10 +33,17 @@
 
 var waitForDone = false;
 
+function sendBackData() {
+  if (window.opener) {
+    window.opener.postMessage(window.document.body.innerHTML, "*");
+  }
+}
+
 function processMessage(msg) {
   if (typeof msg != 'string') return;
   if (msg == 'unittest-suite-done') {
     if (testRunner) testRunner.notifyDone();
+    sendBackData();
   } else if (msg == 'unittest-suite-wait-for-done') {
     waitForDone = true;
     if (testRunner) testRunner.startedDartTest = true;
@@ -49,6 +56,7 @@
   } else if (msg == 'unittest-suite-success') {
     dartPrint('PASS');
     if (testRunner) testRunner.notifyDone();
+    sendBackData();
   } else if (msg == 'unittest-suite-fail') {
     showErrorAndExit('Some tests failed.');
   }
@@ -72,6 +80,7 @@
   // FAIL and will continue polling until one of these words show up.
   dartPrint('FAIL');
   if (testRunner) testRunner.notifyDone();
+  sendBackData();
 }
 
 function onLoad(e) {
@@ -107,6 +116,7 @@
     setTimeout(function() {
       if (testRunner && !testRunner.startedDartTest) {
         testRunner.notifyDone();
+        sendBackData();
       }
     }, 0);
   }, 50);