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

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index fbf3fec6c885ac0f23605ba0b02d93115a996593..3dc54203b17c5de74f7a6ac5a4b2d58fb31c7ee6 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -2685,8 +2685,9 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op) {
       }
       EmitStoreToStackLocalOrContextSlot(var, location);
     }
+  } else if (IsSignallingAssignmentToConst(var, op, strict_mode())) {
+    __ CallRuntime(Runtime::kThrowConstAssignError, 0);
   }
-  // Non-initializing assignments to consts are ignored.
 }