[Interpreter] Adds support for const/let variables to interpreter.

src/interpreter/bytecode-generator.h

Index: src/interpreter/bytecode-generator.h
diff --git a/src/interpreter/bytecode-generator.h b/src/interpreter/bytecode-generator.h
index bb96130460922305e675e3b9863f2dc03957d114..fdaf6c97050e333bd5869576239b7b259a2c149c 100644
--- a/src/interpreter/bytecode-generator.h
+++ b/src/interpreter/bytecode-generator.h
@@ -74,7 +74,13 @@ class BytecodeGenerator final : public AstVisitor {
   MUST_USE_RESULT Register
   VisitVariableLoadForRegisterValue(Variable* variable, FeedbackVectorSlot slot,
                                     TypeofMode typeof_mode = NOT_INSIDE_TYPEOF);
-  void VisitVariableAssignment(Variable* variable, FeedbackVectorSlot slot);
+  void VisitVariableAssignment(Variable* variable, Token::Value op,
+                               FeedbackVectorSlot slot);
+  void BuildThrowIfHole(Handle<String> name);
+  void BuildThrowIfNotHole(Handle<String> name);
+  void BuildThrowReassignConstant(Register destination, Handle<String> name);
+  void BuildThrowReassignConstant(Handle<String> name);
+  void BuildHoleCheckForVariableLoad(VariableMode mode, Handle<String> name);
 
   void VisitArgumentsObject(Variable* variable);
   void VisitThisFunctionVariable(Variable* variable);