harmony-scoping: make assignment to 'const' a late error.

src/full-codegen.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_FULL_CODEGEN_H_
 #define V8_FULL_CODEGEN_H_
 
 #include "src/v8.h"
 
 #include "src/allocation.h"
@@ skipping 568 matching lines @@
   void EmitInlineSmiBinaryOp(BinaryOperation* expr,
                              Token::Value op,
                              OverwriteMode mode,
                              Expression* left,
                              Expression* right);
 
   // Assign to the given expression as if via '='. The right-hand-side value
   // is expected in the accumulator.
   void EmitAssignment(Expression* expr);
 
+  // Shall an error be thrown if assignment with 'op' operation is perfomed
+  // on this variable in given language mode?
+  static bool IsSignallingAssignmentToConst(Variable* var, Token::Value op,
+                                            StrictMode strict_mode) {
+    if (var->mode() == CONST) return op != Token::INIT_CONST;
+
+    if (var->mode() == CONST_LEGACY) {
+      return strict_mode == STRICT && op != Token::INIT_CONST_LEGACY;
+    }
+
+    return false;
+  }
+
   // Complete a variable assignment.  The right-hand-side value is expected
   // in the accumulator.
   void EmitVariableAssignment(Variable* var,
                               Token::Value op);
 
   // Helper functions to EmitVariableAssignment
   void EmitStoreToStackLocalOrContextSlot(Variable* var,
                                           MemOperand location);
 
   // Complete a named property assignment.  The receiver is expected on top
@@ skipping 424 matching lines @@
 
   Address start_;
   Address instruction_start_;
   uint32_t length_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FULL_CODEGEN_H_