Remove some warnings and errors from dart2js.

sdk/lib/_internal/compiler/implementation/closure.dart

Index: sdk/lib/_internal/compiler/implementation/closure.dart
diff --git a/sdk/lib/_internal/compiler/implementation/closure.dart b/sdk/lib/_internal/compiler/implementation/closure.dart
index 3d5feef0376368bca40e3c67adf84a8c80ed7124..e0b895a55a7576f3cd49a83d0c52919c165e018c 100644
--- a/sdk/lib/_internal/compiler/implementation/closure.dart
+++ b/sdk/lib/_internal/compiler/implementation/closure.dart
@@ -505,9 +505,9 @@ class ClosureTranslator extends Visitor {
   }
 
   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,