[Interpreter] Add support for local context loads and stores.

src/compiler/interpreter-assembler.h

Index: src/compiler/interpreter-assembler.h
diff --git a/src/compiler/interpreter-assembler.h b/src/compiler/interpreter-assembler.h
index 11f43ccf2648bcc2d2d36f0764bae61eabc1dcae..d49eb5a4c60136797b1ec1f73167d689e4e2bfe0 100644
--- a/src/compiler/interpreter-assembler.h
+++ b/src/compiler/interpreter-assembler.h
@@ -97,6 +97,8 @@ class InterpreterAssembler {
 
   // Load |slot_index| from |context|.
   Node* LoadContextSlot(Node* context, Node* slot_index);
+  // Stores |value| into |slot_index| of |context|.
+  Node* StoreContextSlot(Node* context, Node* slot_index, Node* value);
 
   // Load the TypeFeedbackVector for the current function.
   Node* LoadTypeFeedbackVector();