Fix invalid read of language mode from StorePropertyParameters.

src/compiler/js-generic-lowering.cc

Index: src/compiler/js-generic-lowering.cc
diff --git a/src/compiler/js-generic-lowering.cc b/src/compiler/js-generic-lowering.cc
index b27e8349225a9fc2aecd18758a56620a7d8be49e..14b251f3bf86c4e74a0ab9cc350208e9bfc0c890 100644
--- a/src/compiler/js-generic-lowering.cc
+++ b/src/compiler/js-generic-lowering.cc
@@ -370,7 +370,7 @@ void JSGenericLowering::LowerJSLoadGlobal(Node* node) {
 void JSGenericLowering::LowerJSStoreProperty(Node* node) {
   CallDescriptor::Flags flags = AdjustFrameStatesForCall(node);
   const StorePropertyParameters& p = StorePropertyParametersOf(node->op());
-  LanguageMode language_mode = OpParameter<LanguageMode>(node);
+  LanguageMode language_mode = p.language_mode();
   // We have a special case where we do keyed stores but don't have a type
   // feedback vector slot allocated to support it. In this case, install
   // the megamorphic keyed store stub which needs neither vector nor slot.