Bug 929200, part 1: Add MOZ_HEAP_ALLOCATOR to stack-only/non-heap analyses, r=Waldo.

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extra : rebase_source : 1ea94cf7a8ab7207d238c65877001549f3f828be
Bug 929200, part 2: Add MOZ_HEAP_ALLOCATOR to JSContext::new_, r=jimb.

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extra : rebase_source : 94273fe87e4e432a493dd55a89a005a89e7bb998