Fast path in advance() should check for semicolon instead of colon.

https://code.google.com/p/esprima/issues/detail?id=534
Revert "Fix escaped identifier being treated as a keyword."

https://code.google.com/p/esprima/issues/detail?id=496
Disallow escaped characters in a regular expression flag.

https://code.google.com/p/esprima/issues/detail?id=503
Fix semicolon handling for expression statement.

When expecting a semicolon, consume it right away if that is the next
token. The check for whether there is a line terminator or not should
only happen afterwards.

https://code.google.com/p/esprima/issues/detail?id=462
https://code.google.com/p/esprima/issues/detail?id=533
Merge branch 'master' into gh-pages