Bug 959787 - Handlify several JSAPI interfaces that can GC, Part 1; r=sfink,Ms2ger

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extra : rebase_source : 0e0e75028f12db9cc4cf612a9205525669b70267
Bug 959787 - Handlify several JSAPI interfaces that can GC, Part 2; r=sfink

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extra : rebase_source : e36c89af9c362e781d9ca9aceee42779258328b5
Bug 959787 - Handlify several JSAPI interfaces that can GC, Part 3; r=sfink

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extra : rebase_source : ace7b0fa6ba93acbf0ec8ecaeb68ffa287a33665