Support local variables in dart2dart.

sdk/lib/_internal/compiler/implementation/dart_backend/backend.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.
 
 part of dart_backend;
 
 // TODO(ahe): This class is simply wrong.  This backend should use
 // elements when it can, not AST nodes.  Perhaps a [Map<Element,
 // TreeElements>] is what is needed.
 class ElementAst {
@@ skipping 218 matching lines @@
     final elementAsts = new Map<Element, ElementAst>();
 
     ElementAst parse(Element element, TreeElements treeElements) {
       Node node;
       if (!compiler.irBuilder.hasIr(element)) {
         node = element.parseNode(compiler);
       } else {
         ir.FunctionDefinition function = compiler.irBuilder.getIr(element);
         tree.Builder builder = new tree.Builder(compiler);
         tree.FunctionDefinition definition = builder.build(function);
-        compiler.tracer.traceCompilation(element.name, null, compiler);
-        compiler.tracer.traceGraph('Tree builder', definition);
-        treeElements = new TreeElementMapping(element);
-        tree.Unnamer unnamer = new tree.Unnamer();
-        unnamer.unname(definition);
-        compiler.tracer.traceGraph('Unnamer', definition);
-        tree.Emitter emitter = new tree.Emitter();
-        node = emitter.emit(element, treeElements, definition);
+        if (definition == null) {
+          node = element.parseNode(compiler);
+        } else {
+          compiler.tracer.traceCompilation(element.name, null, compiler);
+          compiler.tracer.traceGraph('Tree builder', definition);
+          treeElements = new TreeElementMapping(element);
+          tree.Unnamer unnamer = new tree.Unnamer();
+          unnamer.unname(definition);
+          compiler.tracer.traceGraph('Unnamer', definition);
+          tree.Emitter emitter = new tree.Emitter();
+          node = emitter.emit(element, treeElements, definition);
+        }
       }
       return new ElementAst(node, treeElements);
     }
 
     Set<Element> topLevelElements = new Set<Element>();
     Map<ClassElement, Set<Element>> classMembers =
         new Map<ClassElement, Set<Element>>();
 
     // Build all top level elements to emit and necessary class members.
     var newTypedefElementCallback, newClassElementCallback;
@@ skipping 382 matching lines @@
   }
 
   Constant compileMetadata(MetadataAnnotation metadata,
                            Node node,
                            TreeElements elements) {
     return measure(() {
       return constantCompiler.compileMetadata(metadata, node, elements);
     });
   }
 }