Run dart2js tests unmodified in browser.

dart/lib/compiler/implementation/js_backend/emitter.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
 class ClosureInvocationElement extends FunctionElement {
   ClosureInvocationElement(SourceString name,
@@ skipping 1208 matching lines @@
     Element main = compiler.mainApp.find(Compiler.MAIN);
     String mainCall = null;
     if (compiler.isolateLibrary != null) {
       Element isolateMain =
         compiler.isolateLibrary.find(Compiler.START_ROOT_ISOLATE);
       mainCall = buildIsolateSetup(buffer, main, isolateMain);
     } else {
       mainCall = '${namer.isolateAccess(main)}()';
     }
     buffer.add("""
+
+//
+// BEGIN invoke [main].
+//
 if (typeof document != 'undefined' && document.readyState != 'complete') {
   document.addEventListener('readystatechange', function () {
     if (document.readyState == 'complete') {
-      ${mainCall};
+      if (typeof dartMainRunner == 'function') {
+        dartMainRunner(function() { ${mainCall}; });
+      } else {
+        ${mainCall};
+      }
     }
   }, false);
 } else {
-  ${mainCall};
+  if (typeof dartMainRunner == 'function') {
+    dartMainRunner(function() { ${mainCall}; });
+  } else {
+    ${mainCall};
+  }
 }
+//
+// END invoke [main].
+//
+
 """);
   }
 
   String assembleProgram() {
     measure(() {
       mainBuffer.add('function ${namer.ISOLATE}() {}\n');
       mainBuffer.add('init();\n\n');
       // Shorten the code by using "$$" as temporary.
       classesCollector = @"$$";
       mainBuffer.add('var $classesCollector = {};\n');
@@ skipping 65 matching lines @@
         sourceName = token.slowToString();
       }
       sourceMapBuilder.addMapping(
           sourceFile, token.charOffset, sourceName, offset);
     });
     return sourceMapBuilder.build(compiledFile);
   }
 }
 
 typedef void DefineMemberFunction(String invocationName, CodeBuffer definition);