Report a parse error if there is a throw followed by a semicolon or newline.

The grammar has a "[no LineTerminator here]" so "throw;" or "throw \n expr;" are illegal.

https://people.mozilla.org/~jorendorff/es6-draft.html#sec-throw-statement

Fixes #652
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=77109093
Attempt to protect goog.global properties for overwrite with global variables.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=77128870