Bug 1002302 - WebGL2 - Stub WebGL 2.0 WebIDL, WebGL 2.0 Objects, and functions in WebGL2Context.; r=jgilbert,bjacob,smaug

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extra : rebase_source : a7f9510b34a9f43afc0418c50b8821928c2a4262
extra : source : 89c2a61cd4c543c78b9bf0963f0227488fa27802