DeclaredGlobalExternsOnWindow fixes:
- Add '@suppress {duplicate}' in all cases, not just for constructors.
- Don't add a declaration for window.location since it conflicts with an existing one.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67286926
Add chrome.browser.openTab extern declaration.

This API is being added in Chrome 36 (currently enabled only in dev channel).
It only works in packaged apps and requires the "browser" permission.
See https://code.google.com/p/chromium/issues/detail?id=358315 and
https://codereview.chromium.org/245933002
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67288014
Report warnings as they are found.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67296689
[NEW TYPE INFERENCE] Optimize the JSType.toString function.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67298912
[NEW TYPE INFERENCE] Fix a bug in JSType.negate

Knowing that a type is a scalar doesn't mean that it's negation will also be a scalar.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67526660