Auto merge of #464 - servo:jdm-patch-7, r=jdm
Auto merge of #464 - servo:jdm-patch-7, r=jdm

Update mozjs_sys.

This incorporates https://github.com/servo/mozjs/pull/185.

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servo/rust-mozjs,servo/rust-mozjs,servo/rust-mozjs,servo/rust-mozjs