dart2dart: Introduce Renamer that is used by renaming unparser

lib/compiler/implementation/resolver.dart

Index: lib/compiler/implementation/resolver.dart
diff --git a/lib/compiler/implementation/resolver.dart b/lib/compiler/implementation/resolver.dart
index b811b8a4dff3ccd92b08d2d51a07bb6af365c785..2f003b6bff80b012371cacfdf9857e65fb2cc102 100644
--- a/lib/compiler/implementation/resolver.dart
+++ b/lib/compiler/implementation/resolver.dart
@@ -935,6 +935,7 @@ class ResolverVisitor extends CommonResolverVisitor<Element> {
 
   void setupFunction(FunctionExpression node, FunctionElement function) {
     context = new MethodScope(context, function);
+    if (node.returnType !== null) resolveTypeAnnotation(node.returnType);
     // Put the parameters in scope.
     FunctionSignature functionParameters =
         function.computeSignature(compiler);
@@ -946,6 +947,9 @@ class ResolverVisitor extends CommonResolverVisitor<Element> {
       }
       VariableDefinitions variableDefinitions = parameterNodes.head;
       Node parameterNode = variableDefinitions.definitions.nodes.head;
+      if (variableDefinitions.type !== null) {
+        resolveTypeAnnotation(variableDefinitions.type);
+      }
       initializerDo(parameterNode, (n) => n.accept(this));
       // Field parameters (this.x) are not visible inside the constructor. The
       // fields they reference are visible, but must be resolved independently.