[ic] Encode [Keyed]StoreIC's language mode in slot kind instead of code object's flags.

src/full-codegen/full-codegen.cc

Index: src/full-codegen/full-codegen.cc
diff --git a/src/full-codegen/full-codegen.cc b/src/full-codegen/full-codegen.cc
index 8de7eeb02e8ce1fbcd8ea143d752adefe713f3ff..c4909ab9474d3813b664ec8d1f4fb829432118ba 100644
--- a/src/full-codegen/full-codegen.cc
+++ b/src/full-codegen/full-codegen.cc
@@ -230,6 +230,9 @@ void FullCodeGenerator::CallStoreIC(FeedbackVectorSlot slot,
     EmitLoadSlot(StoreDescriptor::SlotRegister(), slot);
   }
 
+  // Ensure that language mode is in sync with the IC slot kind.
+  DCHECK_EQ(GetLanguageModeFromICKind(feedback_vector_spec()->GetKind(slot)),
+            language_mode());
   Handle<Code> code = CodeFactory::StoreIC(isolate(), language_mode()).code();
   __ Call(code, RelocInfo::CODE_TARGET);
   RestoreContext();
@@ -245,6 +248,9 @@ void FullCodeGenerator::CallKeyedStoreIC(FeedbackVectorSlot slot) {
     EmitLoadSlot(StoreDescriptor::SlotRegister(), slot);
   }
 
+  // Ensure that language mode is in sync with the IC slot kind.
+  DCHECK_EQ(GetLanguageModeFromICKind(feedback_vector_spec()->GetKind(slot)),
+            language_mode());
   Handle<Code> code =
       CodeFactory::KeyedStoreIC(isolate(), language_mode()).code();
   __ Call(code, RelocInfo::CODE_TARGET);
@@ -1600,6 +1606,10 @@ bool FullCodeGenerator::has_simple_parameters() {
 
 FunctionLiteral* FullCodeGenerator::literal() const { return info_->literal(); }
 
+const FeedbackVectorSpec* FullCodeGenerator::feedback_vector_spec() const {
+  return literal()->feedback_vector_spec();
+}
+
 #undef __