Bug 959787 - Handlify several JSAPI interfaces that can GC, Part 4; r=sfink,r=bz

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extra : rebase_source : 8e1ff566f47795cd82e3f4c0a6fa37b88e7847b4
Bug 959787 - Handlify several JSAPI interfaces that can GC, Part 5; r=jonco

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extra : rebase_source : 13c96b6118408cfb001a3191871cbf7ce4d8a2c3