Bug 1048747 - WebGL2 - GL symbols for GetIntegeri_v and GetInteger64i_v.; r=jgilbert

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extra : rebase_source : d4c5a1a6e4a5c6f772a4f69c2ff3edab50d0d6e4
extra : source : 9929d6519682ca1b0dac4e7390349a2254d711c5