Support parameter metadata.

sdk/lib/_internal/compiler/implementation/dart_backend/utils.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/utils.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/utils.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/utils.dart
index 6b885d6f48baa2deca30b866c82e7c76962b03e5..14a2cc9012bd75bce9010f60505a6873cc3e9dae 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/utils.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_backend/utils.dart
@@ -117,6 +117,9 @@ class CloningVisitor implements Visitor<Node> {
   visitLiteralString(LiteralString node) => new LiteralString(
       node.token, node.dartString);
 
+  visitMetadata(Metadata node) => new Metadata(
+      node.token, visit(node.expression));
+
   visitMixinApplication(MixinApplication node) => new MixinApplication(
       visit(node.superclass), visit(node.mixins));
 
@@ -213,8 +216,10 @@ class CloningVisitor implements Visitor<Node> {
   visitTypeVariable(TypeVariable node) => new TypeVariable(
       visit(node.name), visit(node.bound));
 
-  visitVariableDefinitions(VariableDefinitions node) => new VariableDefinitions(
-      visit(node.type), visit(node.modifiers), visit(node.definitions));
+  visitVariableDefinitions(VariableDefinitions node) =>
+      new VariableDefinitions.forParameter(
+          visit(node.metadata), visit(node.type),
+          visit(node.modifiers), visit(node.definitions));
 
   visitWhile(While node) => new While(
       visit(node.condition), visit(node.body), node.whileKeyword);