Added missing chrome.tabs.onReplaced extern.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54199598
Remove trailing space.

-------------
Created by MOE: http://code.google.com/p/moe-java
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54239147
Remove incorrect @override declaration on MessageEvent.prototype.initMessageEvent.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54602128
Add DOM traversal interface to javascript externs -- adds createNodeIterator and createTreeWalker.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54682338
Merge remote-tracking branch: upstream/master