Mark TypedRect as repr(C)

[eqrion]

TypedPoint2D and TypedSize2D are both repr(C) so TypedRect can be marked repr(C). This helps improve the FFI interface for WebRender.

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This change is 

[emilio]

@bors-servo r+

[bors-servo]

📌 Commit 6c00093 has been approved by emilio

[bors-servo]

⌛ Testing commit 6c00093 with merge 1d5fb01...

[emilio]

Thanks!

[bors-servo]

☀️ Test successful - status-travis
Approved by: emilio
Pushing 1d5fb01 to master...

[kvark]

@nical I hate to say it, but isn't adding repr() technically making this a breaking change?..

[nical]

I don't think so. As long as there is no repr specified the representation isn't defined, so code that relies on the representation is already technically invalid. It could have been a breaking change if the type already had an explicit repr and we had changed it.
Also, in practice the actual representation has not changed in that case anyway, so it isn't possible that this has broken any code as far as I know.

[eqrion]

@nical It would be nice to get a version with this used by webrender, so it can make its way over to gecko eventually.

Not sure how much work that is, it's not urgent.

[nical]

I think that the only thing we need to do is bump euclid to 0.15.1 and have webrender depend on 0.15.1 instead of 0.15.0 (since there was no breaking change as far as I can tell).