Port `id` attribute to use atom.
Bump submodule ptr to get texture filter fixes in rust-layers.
Implement the delete proxy trap (fixes #2213).
Merge pull request #2947 from Ms2ger/delete-trap

Implement the delete proxy trap (fixes #2213); r=jdm
Merge pull request #2946 from glennw/update-layers

Bump submodule ptr to get texture filter fixes in rust-layers.
Change Box to Fragment in fragment.rs doc comment
Use atom to match id selector.
Merge pull request #2952 from mbrubeck/fragment-comment

Update fragment.rs doc comment with new type name (Box -> Fragment)
Merge pull request #2927 from saneyuki/id_atom

Port `id` attribute to use atom.
Use === for is() and is_not() in contenttests.

The notion of equality used by == in JavaScript is not useful for testing.
Merge pull request #2957 from Ms2ger/is-is_not

Use === for is() and is_not() in contenttests.
Sort MANIFEST.json.

This avoids spurious changes when updating it.
Update update_manifest() for upstream changes.
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