Allow a closure to be torn off from itself via .call.

sdk/lib/_internal/compiler/implementation/js_emitter/class_emitter.dart

 // Copyright (c) 2013, 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.
 
 part of dart2js.js_emitter;
 
 class ClassEmitter extends CodeEmitterHelper {
   /**
    * Documentation wanted -- johnniwinther
    *
@@ skipping 29 matching lines @@
     emitClassConstructor(classElement, builder, runtimeName,
                          onlyForRti: onlyForRti);
     emitFields(classElement, builder, superName, onlyForRti: onlyForRti);
     emitClassGettersSetters(classElement, builder, onlyForRti: onlyForRti);
     emitInstanceMembers(classElement, builder, onlyForRti: onlyForRti);
     task.typeTestEmitter.emitIsTests(classElement, builder);
     if (additionalProperties != null) {
       additionalProperties.forEach(builder.addProperty);
     }
 
+    if (classElement == compiler.closureClass) {
+      // We add a special getter here to allow for tearing off a closure form

[karlklose, 2014/04/28 07:04:23]

'form' -> 'from'.

+      // itself.
+      String name = namer.safeName(Compiler.CALL_OPERATOR_NAME);
+      jsAst.Fun function = js('function() { return this; }');
+      builder.addProperty(namer.getterNameFromAccessorName(name), function);
+    }
+
     emitTypeVariableReaders(classElement, builder);
 
     emitClassBuilderWithReflectionData(
         className, classElement, builder, properties);
   }
 
   void emitClassConstructor(ClassElement classElement,
                             ClassBuilder builder,
                             String runtimeName,
                             {bool onlyForRti: false}) {
@@ skipping 552 matching lines @@
       computeTypeVariable =
           js(r'this.$builtinTypeInfo && this.$builtinTypeInfo[#]', index);
     }
     jsAst.Expression convertRtiToRuntimeType =
         namer.elementAccess(compiler.findHelper('convertRtiToRuntimeType'));
     builder.addProperty(name,
         js('function () { return #(#) }',
             [convertRtiToRuntimeType, computeTypeVariable]));
   }
 }