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

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index df3144882686f312dfc3e9dd72c1de98ddbc74de..d3cfab82e10a08dd2d2c5abba3bb107c64438c4f 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -2745,6 +2745,8 @@ Node* AstGraphBuilder::BuildNamedLoad(Node* object, Handle<Name> name,
 
 Node* AstGraphBuilder::BuildKeyedStore(Node* object, Node* key, Node* value,
                                        const VectorSlotPair& feedback) {
+  DCHECK_EQ(feedback.vector()->GetLanguageMode(feedback.slot()),
+            language_mode());
   const Operator* op = javascript()->StoreProperty(language_mode(), feedback);
   Node* node = NewNode(op, object, key, value);
   return node;
@@ -2754,6 +2756,8 @@ Node* AstGraphBuilder::BuildKeyedStore(Node* object, Node* key, Node* value,
 Node* AstGraphBuilder::BuildNamedStore(Node* object, Handle<Name> name,
                                        Node* value,
                                        const VectorSlotPair& feedback) {
+  DCHECK_EQ(feedback.vector()->GetLanguageMode(feedback.slot()),
+            language_mode());
   const Operator* op =
       javascript()->StoreNamed(language_mode(), name, feedback);
   Node* node = NewNode(op, object, value);