Implement argument definition test in the vm.

runtime/vm/parser.h

Index: runtime/vm/parser.h
===================================================================
--- runtime/vm/parser.h	(revision 11663)
+++ runtime/vm/parser.h	(working copy)
@@ -68,6 +68,10 @@
     saved_context_var_ = saved_context_var;
   }
 
+  // Returns NULL if this function does not save the arguments descriptor on
+  // entry.
+  LocalVariable* GetSavedArgumentsDescriptorVar() const;
+
   LocalVariable* expression_temp_var() const {
     ASSERT(has_expression_temp_var());
     return expression_temp_var_;
@@ -459,6 +463,7 @@
                            bool is_const,
                            const AbstractTypeArguments& type_arguments);
   AstNode* ParseNewOperator();
+  AstNode* ParseArgumentDefinitionTest();
 
   // An implicit argument, if non-null, is prepended to the returned list.
   ArgumentListNode* ParseActualParameters(ArgumentListNode* implicit_arguments,
@@ -476,6 +481,10 @@
                                   bool consume_cascades);
 
   LocalVariable* LookupLocalScope(const String& ident);
+  bool IsFormalParameter(const String& ident,
+                         Function* owner_function,
+                         LocalScope** owner_scope,
+                         intptr_t* local_index);
   void CheckInstanceFieldAccess(intptr_t field_pos, const String& field_name);
   RawClass* TypeParametersScopeClass() const;
   const Type* ReceiverType(intptr_t type_pos) const;