Typecheck chrome://help using CompilerPass.java, everything except dependency to options

ui/webui/resources/js/assert.js

 // Copyright (c) 2013 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.
 
 /**
  * @fileoverview Assertion support.
  */
 
 /**
  * Simple common assertion API
@@ skipping 29 matching lines @@
  *   }
  *
  * This code should only be hit in the case of serious programmer error or
  * unexpected input.
  *
  * @param {string=} opt_message A message to show when this is hit.
  */
 function assertNotReached(opt_message) {
   throw new Error(opt_message || "Unreachable code hit");
 }
+
+/**
+ * @param {*} value The value to check.
+ * @param {function(new: T, ...)} type A user-defined constructor.
+ * @return {!T}
+ * @template T
+ */
+function assertInstanceof(value, type) {
+  if (!(value instanceof type)) {

[Dan Beam, 2014/08/13 22:20:08]

nit: no curlies

[Vitaly Pavlenko, 2014/08/14 00:01:02]

Done.

+    throw new Error('assertInstanceof');

[Dan Beam, 2014/08/13 22:20:07]

throw new Error(value + ' is not a[n] ' + (type.name || typeof type));

[Vitaly Pavlenko, 2014/08/14 00:01:02]

Done.

+  }
+  return value;
+}