Support for "a is Function".

frog/leg/compiler.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 WorkItem {
   final Element element;
   TreeElements resolutionTree;
   Function run;
   Map<int, BailoutInfo> bailouts = null;
   bool allowSpeculativeOptimization = true;
@@ skipping 35 matching lines @@
 
   final Tracer tracer;
 
   CompilerTask measuredTask;
   Element _currentElement;
   LibraryElement coreLibrary;
   LibraryElement coreImplLibrary;
   LibraryElement jsHelperLibrary;
   LibraryElement mainApp;
   ClassElement objectClass;
+  ClassElement closureClass;
 
   Element get currentElement() => _currentElement;
   withCurrentElement(Element element, f()) {
     Element old = currentElement;
     _currentElement = element;
     try {
       return f();
     } finally {
       _currentElement = old;
     }
@@ skipping 11 matching lines @@
   SsaCodeGeneratorTask generator;
   CodeEmitterTask emitter;
   ConstantHandler constantHandler;
   EnqueueTask enqueuer;
 
   static final SourceString MAIN = const SourceString('main');
   static final SourceString NO_SUCH_METHOD = const SourceString('noSuchMethod');
   static final SourceString NO_SUCH_METHOD_EXCEPTION =
       const SourceString('NoSuchMethodException');
   static final SourceString OBJECT = const SourceString('Object');
+  static final SourceString CLOSURE = const SourceString('Closure');
   bool enabledNoSuchMethod = false;
 
   static final String GREEN_COLOR = '\u001b[32m';
   static final String RED_COLOR = '\u001b[31m';
   static final String MAGENTA_COLOR = '\u001b[35m';
   static final String NO_COLOR = '\u001b[0m';
 
   Compiler.withCurrentDirectory(String this.currentDirectory,
                                 [this.tracer = const Tracer()])
       : types = new Types(),
@@ skipping 85 matching lines @@
     invocations.add(new Invocation(2));
   }
 
   abstract LibraryElement scanBuiltinLibrary(String filename);
 
   void scanBuiltinLibraries() {
     coreImplLibrary = scanBuiltinLibrary('coreimpl.dart');
     jsHelperLibrary = scanBuiltinLibrary('js_helper.dart');
     coreLibrary = scanBuiltinLibrary('core.dart');
     objectClass = coreLibrary.find(OBJECT);
+    closureClass = jsHelperLibrary.find(CLOSURE);
     // Since coreLibrary import the libraries "coreimpl", and
     // "js_helper", coreLibrary is null when they are being built. So
     // we add the implicit import of coreLibrary now. This can be
     // cleaned up when we have proper support for "dart:core" and
     // don't need to access it through the field "coreLibrary".
     // TODO(ahe): Clean this up as described above.
     scanner.importLibrary(coreImplLibrary, coreLibrary, null);
     scanner.importLibrary(jsHelperLibrary, coreLibrary, null);
     addForeignFunctions(jsHelperLibrary);
 
@@ skipping 248 matching lines @@
   }
 }
 
 class SourceSpan {
   final Uri uri;
   final int begin;
   final int end;
 
   const SourceSpan(this.uri, this.begin, this.end);
 }