Bug 897718 - Remove unused JSAPI method JS_CallGenericTracer; r=jonco

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extra : rebase_source : 42641b92f4228a6cbccc9c7c6d16333308748a80
Bug 897724 - Fix some opt build warnings in clang; r=sfink

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extra : rebase_source : af3aa90d6464fd6701e29d014782a9037a3b1afe