Bug 853028 - Add JSID_VOIDHANDLE and JSID_EMPTYHANDLE r=terrence

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extra : rebase_source : df2040a51dff433c59356092d55dad65097b8994
Bug 853028 - GC: Fix some rooting issues found by static analysis r=terrence

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extra : rebase_source : a1d340a00516ae890c98fa7420497e85526823fc