Remove unused code (4/4)
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Fourth and final PR in a series of PRs to remove unused/dead code from servo, powered by an (upcoming) tool of mine. Please take a look and tell me if you want to keep something.
* First PR: #23477
* Second PR: #23498
* Third PR: #23499
Shortstat of the combined PR series:
```
47 files changed, 7 insertions(+), 805 deletions(-)
```
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- [x] `./mach test-tidy` does not report any errors
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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because they only remove dead code
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The alias is left there temporarilly and will be removed completely in a later commit where
also components/style/gecko/generated/structs_{debug|release}.rs are re-generated (they still
use the old alias).
This reverts commit ebfc8f5858, reversing
changes made to 5585ff2c44.
Animation code can reenter and create a new TLS context from the traversal
SequentialTask, so this won't work as written.
This is important because we're about to start storing a parallel list
of pushed hashes, and the current behavior here will cause mismatches
there.
We take the opportunity to bump the SmallVec size to 16, since each
entry is only a word and we really want to avoid heap-allocating. And
then we switch to drain(), because of
https://github.com/rust-lang/rust/issues/42763
This patch renames TNode::parent_element to traversal_parent, since it returns
the parent from the perspective of traversal (which in Gecko uses the
flattened tree). It also renames TNode::children to traversal_children
for the saem reason.
We keep parent_element and children functions on TNode to use for selector
matching, which must be done on the real DOM tree structure.
We can have cousins in the cache whose parent doesn't match ours, and other
cousins whose parent does. When we encounter one of the former, that's not a
reason to stop lookin for the latter.
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1369620
While we're at it, we also eliminate the 'unknown' dom depth for the
bloom filter. Computing depth has negligible cost relative to the
amount of work we do setting up the bloom filter at a given depth.
Doing it once per traversal should be totally fine.
I originally separated the elimination of unknown dom depth from the
traversal changes, but I got bloom filter crashes on the intermediate
patch, presumably because I didn't properly fix the sequential traversal
for this case. Given that the final state is green, I just decided to
squash and move on.
We need to do something here to avoid a double-borrow when passing a mutable
StyleContext to match_element. After some discussion on IRC, we decided that
building the bloom filter for this case is probably worthwhile.
This is not a problem for Servo, because we recovered it without much problem a
few lines below, and we never reached the pathological case where the filter has
one element (the root), and we restyled another element with depth 1.
Fixes bug 1321725.
