Update platform_app.js to work even if window.history is not replaceable

chrome/test/data/extensions/platform_apps/restrictions/main.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var assertEq = chrome.test.assertEq;
 var assertTrue = chrome.test.assertTrue;
 var fail = chrome.test.fail;
 var succeed = chrome.test.succeed;
 
 function assertThrowsError(method, opt_expectedError) {
@@ skipping 44 matching lines @@
     assertEq('undefined', typeof(document.bgColor));
     assertEq('undefined', typeof(document.fgColor));
     assertEq('undefined', typeof(document.alinkColor));
     assertEq('undefined', typeof(document.linkColor));
     assertEq('undefined', typeof(document.vlinkColor));
 
     succeed();
   },
 
   function testHistory() {
-    // Accessing these logs warnings to the console.
-    assertEq('undefined', typeof(history.back));
-    assertEq('undefined', typeof(history.forward));
-    assertEq('undefined', typeof(history.length));
+    // History API should be disabled (e.g. Accessing these logs warnings to
+    // the console).
+    for (var property in history) {
+      assertEq('undefined', typeof(history[property]));

[Inactive, 2014/04/21 19:46:10]

This is a bit safer now, in case new properties / methods are added to History
but we don't explicitly disable them in platform_app.js (as we now have to
disable / remove API explicitly).

Also, this adds coverage for history.go(), which was not tested before but
should be disabled.

+    }
 
     // These are part of the HTML5 History API that are feature detected, so we
     // remove them altogether, allowing apps to have fallback behavior.
     chrome.test.assertFalse('pushState' in history);
     chrome.test.assertFalse('replaceState' in history);
     chrome.test.assertFalse('state' in history);
 
     succeed();
   },
 
@@ skipping 108 matching lines @@
     assertEq('undefined', typeof(chrome.extension));
     succeed();
   },
 
   function testExtensionApis() {
     assertEq('undefined', typeof(chrome.tabs));
     assertEq('undefined', typeof(chrome.windows));
     succeed();
   }
 ]);