InvocationMirror implemented in dart2js.

lib/compiler/implementation/enqueue.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.
 
 class EnqueueTask extends CompilerTask {
   final Enqueuer codegen;
   final Enqueuer resolution;
 
   String get name => 'Enqueue';
 
@@ skipping 229 matching lines @@
     });
   }
 
   void registerNewSelector(SourceString name,
                            Selector selector,
                            Map<SourceString, Set<Selector>> selectorsMap) {
     if (name != selector.name) {
       String message = "$name != ${selector.name} (${selector.kind})";
       compiler.internalError("Wrong selector name: $message.");
     }
+    if (!compiler.enabledInvokeOn && name == Compiler.INVOKE_ON) {
+      if (selector.applies(compiler.invokeOnMethod, compiler)) {

[bakster, 2012/10/24 13:43:04]

Why two if statements when you have three expressions.
Consider using one if. 

[Johnni Winther, 2012/10/25 13:34:56]

Test removed.

+        compiler.enabledInvokeOn = true;
+      }
+    }
     Set<Selector> selectors =
         selectorsMap.putIfAbsent(name, () => new Set<Selector>());
     if (!selectors.contains(selector)) {
       selectors.add(selector);
       handleUnseenSelector(name, selector);
     }
   }
 
   void registerInvocation(SourceString methodName, Selector selector) {
     task.measure(() {
@@ skipping 102 matching lines @@
 
   String toString() => 'Enqueuer($name)';
 
   registerUsedSelector(Selector selector) {
     Element interceptor = compiler.backend.getInterceptor(selector);
     if (interceptor != null) {
       registerStaticUse(interceptor);
     }
   }
 }