TypeScript React grammar services both Javascript and TypeScript React languages.

The grammar can be updated by:

* Copy the latest from TypeScript-TMLanguage repo to this folder (including the TypeScriptReactGrammar).
* Add fileType's js and jsx to the filetypes string array in the TypeScriptReactGrammar.

These same actions are automated in the TS workload for VS:
https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_git/Typescript?path=%2FVS%2Fscripts%2FsyncGrammar.ps1&version=GBmaster-dev15&_a=contents

TODO: perhaps automate our updates as well.