Ship ES2015 sloppy-mode const semantics

test/mjsunit/es6/block-eval-var-over-legacy-const.js

 // Copyright 2015 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.
 
 // Flags: --harmony-sloppy --harmony-sloppy-let --harmony-sloppy-function
+// Flags: --legacy-const
 
-// Var-let conflict in a function throws, even if the var is in an eval
+// Legacy-const-let conflict in a function throws, even if the legacy const
+// is in an eval
 
 // Throws at the top level of a function
 assertThrows(function() {
   let x = 1;
   eval('const x = 2');
 }, TypeError);
 
 // If the eval is in its own block scope, throws
 assertThrows(function() {
   let y = 1;
@@ skipping 31 matching lines @@
 try {
   let a = 1;
   (function() {
     eval('const a');
   })();
 } catch (e) {
   caught = true;
 }
 assertFalse(caught);
 
-// var across with doesn't conflict
+// legacy const across with doesn't conflict
 caught = false;
 try {
   (function() {
     with ({x: 1}) {
       eval("const x = 2;");
     }
   })();
 } catch (e) {
   caught = true;
 }
 assertFalse(caught);
 
-// var can still conflict with let across a with
+// legacy const can still conflict with let across a with
 caught = false;
 try {
   (function() {
     let x;
     with ({x: 1}) {
       eval("const x = 2;");
     }
   })();
 } catch (e) {
   caught = true;
 }
 assertTrue(caught);