Disable const in strict mode.

test/mjsunit/strict-mode.js

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 262 matching lines @@
 CheckStrictMode("function strict() { var x = ++arguments; }", SyntaxError);
 
 // Prefix decrement with eval or arguments
 CheckStrictMode("function strict() { --eval; }", SyntaxError);
 CheckStrictMode("function strict() { --arguments; }", SyntaxError);
 CheckStrictMode("function strict() { print(--eval); }", SyntaxError);
 CheckStrictMode("function strict() { print(--arguments); }", SyntaxError);
 CheckStrictMode("function strict() { var x = --eval; }", SyntaxError);
 CheckStrictMode("function strict() { var x = --arguments; }", SyntaxError);
 
+// Use of const in strict mode is disallowed in anticipation of ES Harmony.
+CheckStrictMode("const x = 0;", SyntaxError);
+CheckStrictMode("for (const x = 0; false;) {}", SyntaxError);
+CheckStrictMode("function strict() { const x = 0; }", SyntaxError);
+
 // Delete of an unqualified identifier
 CheckStrictMode("delete unqualified;", SyntaxError);
 CheckStrictMode("function strict() { delete unqualified; }", SyntaxError);
 CheckStrictMode("function function_name() { delete function_name; }",
                 SyntaxError);
 CheckStrictMode("function strict(parameter) { delete parameter; }",
                 SyntaxError);
 CheckStrictMode("function strict() { var variable; delete variable; }",
                 SyntaxError);
 CheckStrictMode("var variable; delete variable;", SyntaxError);
@@ skipping 400 matching lines @@
       assertEquals(callIndexedNonStrictGet(false), "object");
 
     }
   } finally {
     // Cleanup
     cleanup(String);
     cleanup(Number);
     cleanup(Boolean);
   }
 })();