Automated g4 rollback of changelist 54802220.

*** Reason for rollback ***

breakages

*** Original change description ***

Check for unnecessary casts in the TypeCheck pass.

***
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54829791
Externs file for the latest version of underscore (1.5.2).
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54891014
Add on, off, and triggerHandler methods to angular.JQLite typedef.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54911107
Fix wrong declaration in w3c_audio.js.

AudioContext.prototype.createChannelSplitter and AudioContext.prototype.createChannelMerger can both take an optional number parameter.

https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#AudioContext-section
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=54916382
chrome.fileSystem API: Revise the use of Entry vs. FileEntry and allow
nullable Entry in chooseEntry callback.

In chooseEntry's callback, the first Entry arg in the callback turns out
to be passed null when the user cancels the chooseEntry Save File dialog.
The API docs confirm that the Entry passed to the callback can indeed be
optional and null.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=55035956
Add ECMA-402 definition of Date.toLocaleString
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=55041968
Merge remote-tracking branch: upstream/master