Bug 993075 - Change FinishTakingSrcNotes to return bool and take an outparam for the source note count. r=luke

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extra : rebase_source : 604fd7221d6fc3cd71e44cecb374640ed82c12f6
Bug 988416 - Part 1: Extract self-hosting #defines into builtin/SelfHostingDefines.h. r=jwalden

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extra : rebase_source : 73008ee9e390a527bdc48d27c6ee499b8593b983
Bug 988416 - Part 2: Add safe _DefineValueProperty self-hosting intrinsic. r=jwalden

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extra : rebase_source : 029e4b5f57b692657b55781959e65c59ebfe355e