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Pulls https://github.com/servo/rust-mozjs/pull/398 and aims to close https://github.com/servo/rust-mozjs/issues/343.
We can't convert from `JSVal` to `Heap<JSVal>` safely (due to GC barriers we can't move Heap value after changing its underlying value to something meaningful, e.g. non-null or non-undefined), so I decided to also wrap the Heap values in a Box (and in dictionaries in RootedTraceableBox, see https://github.com/servo/servo/pull/20265#issuecomment-372838379 and the issue for more details) in dictionaries.
Since we allocate more to be safe, I think it'd be good to also do some sort of a JS perf run, if there is any to see if there's any significant overhead.
r? @jdm
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- [X] `./mach build -d` does not report any errors
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- [ ] These changes fix #__ (github issue number if applicable).
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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because checking for not moving Heap after setting a value would require encoding a lot more info in type system (Heap) and I'm not sure how to do that and end up with an ergonomic and consistent API
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Source-Repo: https://github.com/servo/servo
Source-Revision: 23b6f569d09f9b10a70ca1b5c8a48f7da45853e2
e87d425d2d