test: fix tests after V8 upgrade

- An error message changed for undefined references
- `let` is now allowed in sloppy mode
- ES2015 proxies are shipped and the `Proxy` global is now a function

PR-URL: https://github.com/nodejs/node/pull/4722
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>

test/message/timeout_throw.out

@@ -2,6 +2,6 @@
   undefined_reference_error_maker;
   ^
 ReferenceError: undefined_reference_error_maker is not defined
-    at null._onTimeout (*test*message*timeout_throw.js:*:*)
+    at ._onTimeout (*test*message*timeout_throw.js:*:*)
     at tryOnTimeout (timers.js:*:*)
     at Timer.listOnTimeout (timers.js:*:*)

test/parallel/test-repl-mode.js

@@ -28,8 +28,7 @@ function testSloppyMode() {
   cli.input.emit('data', `
     let y = 3
   `.trim() + '\n');
-  assert.ok(/SyntaxError: Block-scoped/.test(
-      cli.output.accumulator.join('')));
+  assert.equal(cli.output.accumulator.join(''), 'undefined\n> ');
 }
 
 function testStrictMode() {

test/parallel/test-repl-tab-complete.js

@@ -1,7 +1,5 @@
 'use strict';
 
-// Flags: --harmony-proxies
-
 var common = require('../common');
 var assert = require('assert');
 var repl = require('repl');

test/parallel/test-vm-proxies.js

@@ -1,5 +1,4 @@
 'use strict';
-// Flags: --harmony_proxies
 
 require('../common');
 var assert = require('assert');
@@ -9,11 +8,11 @@ var vm = require('vm');
 // context.  Make sure that the new context has a Proxy object of its own.
 var sandbox = {};
 vm.runInNewContext('this.Proxy = Proxy', sandbox);
-assert(typeof sandbox.Proxy === 'object');
+assert(typeof sandbox.Proxy === 'function');
 assert(sandbox.Proxy !== Proxy);
 
 // Unless we copy the Proxy object explicitly, of course.
 sandbox = { Proxy: Proxy };
 vm.runInNewContext('this.Proxy = Proxy', sandbox);
-assert(typeof sandbox.Proxy === 'object');
+assert(typeof sandbox.Proxy === 'function');
 assert(sandbox.Proxy === Proxy);