Better placement of argument pushing for a few hydrogen call instructions.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 88413ed9d251b60cc924e3fa38b9b0893c6e0f91..9e3f316e7b6d1603496bb3f9256b9c9384b39733 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -816,8 +816,9 @@ class HGraphBuilder: public AstVisitor {
                        HBasicBlock* false_block);
 
   // Visit an argument subexpression and emit a push to the outgoing
-  // arguments.
-  void VisitArgument(Expression* expr);
+  // arguments.  Returns the hydrogen value that was pushed.
+  HValue* VisitArgument(Expression* expr);
+
   void VisitArgumentList(ZoneList<Expression*>* arguments);
 
   // Visit a list of expressions from left to right, each in a value context.