[PATCH] Added LanguageStandard::LS_JavaScript to gate all JS-specific parsing.

[Daniel Jasper]

  After thinking some more, I guess my main reason is that I strongly doubt
  that we'll ever have a JavaScript style and a C++ style that are identical
  in all aspects other than the LanguageStandard.. So, the detection based on
  the file extension inside clang-format will likely be redundant..

http://llvm-reviews.chandlerc.com/D2242