Remove some warnings and errors from dart2js.

sdk/lib/_internal/compiler/implementation/closure.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.
 
 library closureToClassMapper;
 
 import "elements/elements.dart";
 import "dart2jslib.dart";
 import "tree/tree.dart";
 import "util/util.dart";
@@ skipping 487 matching lines @@
       SourceString surroundingName =
           Elements.operatorNameToIdentifier(enclosingElement.name);
       parts = parts.prepend(surroundingName.slowToString());
     }
     StringBuffer sb = new StringBuffer();
     parts.printOn(sb, '_');
     return sb.toString();
   }
 
   ClosureClassMap globalizeClosure(FunctionExpression node, Element element) {
-    SourceString closureName = new SourceString(closureName(element));
+    SourceString name = new SourceString(closureName(element));
     ClassElement globalizedElement = new ClosureClassElement(
-        closureName, compiler, element, element.getCompilationUnit());
+        name, compiler, element, element.getCompilationUnit());
     FunctionElement callElement =
         new FunctionElement.from(Compiler.CALL_OPERATOR_NAME,
                                  element,
                                  globalizedElement);
     globalizedElement.backendMembers =
         const Link<Element>().prepend(callElement);
     // The nested function's 'this' is the same as the one for the outer
     // function. It could be [null] if we are inside a static method.
     Element thisElement = closureData.thisElement;
     return new ClosureClassMap(element, globalizedElement,
@@ skipping 94 matching lines @@
   }
 
   visitTryStatement(TryStatement node) {
     // TODO(ngeoffray): implement finer grain state.
     bool oldInTryStatement = inTryStatement;
     inTryStatement = true;
     node.visitChildren(this);
     inTryStatement = oldInTryStatement;
   }
 }