Use closure conversion in new dart2js backend.

pkg/compiler/lib/src/js_backend/codegen/task.dart

 // Copyright (c) 2014, 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.
 
 /// Generate code using the cps-based IR pipeline.
 library code_generator_task;
 
 import 'glue.dart';
 import 'codegen.dart';
 import 'unsugar.dart';
@@ skipping 26 matching lines @@
   final IrBuilderTask irBuilderTask;
   final ConstantSystem constantSystem;
   final Compiler compiler;
   final Glue glue;
 
   TypeSystem types;
 
   // TODO(karlklose,sigurm): remove and update dart-doc of [compile].
   final FunctionCompiler fallbackCompiler;
 
-  // TODO(sigurdm): Assign this.
-  Tracer tracer;
+  Tracer get tracer => compiler.tracer;
 
   CspFunctionCompiler(Compiler compiler, JavaScriptBackend backend)
       : irBuilderTask = new IrBuilderTask(compiler),
         fallbackCompiler = new ssa.SsaFunctionCompiler(backend, true),
         constantSystem = backend.constantSystem,
         compiler = compiler,
         glue = new Glue(compiler);
 
   String get name => 'CPS Ir pipeline';
 
@@ skipping 32 matching lines @@
 
   void traceGraph(String title, var irObject) {
     if (tracer != null) {
       tracer.traceGraph(title, irObject);
     }
   }
 
   cps.FunctionDefinition compileToCpsIR(AstElement element) {
     // TODO(sigurdm): Support these constructs.
     if (element.isGenerativeConstructorBody ||
-        element.enclosingClass is ClosureClassElement ||
         element.isNative ||
         element.isField) {
       giveUp('unsupported element kind: ${element.name}:${element.kind}');
     }
 
     cps.FunctionDefinition cpsNode = irBuilderTask.buildNode(element);
     if (cpsNode == null) {
       giveUp('unable to build cps definition of $element');
     }
+    traceGraph("IR Builder", cpsNode);
     new UnsugarVisitor(glue).rewrite(cpsNode);
+    traceGraph("Unsugaring", cpsNode);
     return cpsNode;
   }
 
   static const Pattern PRINT_TYPED_IR_FILTER = null;
 
   String formatTypeMask(TypeMask type) {
     if (type is UnionTypeMask) {
       return '[${type.disjointMasks.map(formatTypeMask).join(', ')}]';
     } else if (type is FlatTypeMask) {
       if (type.isEmpty) {
         return "null";
       }
       String suffix = (type.isExact ? "" : "+") + (type.isNullable ? "?" : "!");
       return '${type.base.name}$suffix';
     } else if (type is ForwardingTypeMask) {
       return formatTypeMask(type.forwardTo);
     }
     throw 'unsupported: $type';
   }
 
   cps.FunctionDefinition optimizeCpsIR(cps.FunctionDefinition cpsNode) {
     // Transformations on the CPS IR.
-    traceGraph("IR Builder", cpsNode);
 
     TypePropagator typePropagator = new TypePropagator<TypeMask>(
         compiler.types,
         constantSystem,
         new TypeMaskSystem(compiler),
         compiler.internalError);
     typePropagator.rewrite(cpsNode);
     traceGraph("Sparse constant propagation", cpsNode);
 
     if (PRINT_TYPED_IR_FILTER != null &&
@@ skipping 82 matching lines @@
       endSourcePosition =
           new TokenSourceFileLocation(sourceFile, endToken, name);
     }
     return node.withPosition(sourcePosition, endSourcePosition);
   }
 
   SourceFile sourceFileOfElement(Element element) {
     return element.implementation.compilationUnit.script.file;
   }
 }