[NEW TYPE INFERENCE] Optimize ObjectType.isSubtypeOf
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67850222
Add debugging output when no files are matched.

At present, all paths are prefaced with "./", which is unclear to the
user of the CLI. He/she has no way of knowing this without trial and error
or reading the code.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67859831
Don't crash on "export = 1;" report a parse error instead.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67865511
Add preliminary support for goog.module.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67868059
Add support for ES6 spread array literals
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=67871725