Simplify CheckPrototypeMaps.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 5da3da54eea2409ced27126b90bac184d540bab0..94137b6b04fa83dc441cfc249473fb195f82b8f5 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -3795,9 +3795,9 @@ void HGraphBuilder::AddCheckConstantFunction(Call* expr,
     AddInstruction(new HCheckMap(receiver, receiver_map));
   }
   if (!expr->holder().is_null()) {
-    AddInstruction(new HCheckPrototypeMaps(receiver,
-                                           expr->holder(),
-                                           receiver_map));
+    AddInstruction(new HCheckPrototypeMaps(
+        Handle<JSObject>(JSObject::cast(receiver_map->prototype())),
+        expr->holder()));
   }
 }