commit 4e64b646662678a6ba01e7fd5847fd8bdbf47fb2
author Mason Freed <masonf@chromium.org> Wed Oct 04 17:40:56 2023
committer Blink WPT Bot <blink-w3c-test-autoroller@chromium.org> Wed Oct 04 17:59:29 2023
tree fcc7f09753e721829cf8c5c0ebfcb4a784d8d862
parent 161e1f9770abe9f9667e658a9c9b88039a6ab65b

Optimize several things about DOM Parts [2/2]

This CL continues the optimization work, with these changes:
- Replace ClonePartsFrom() with PartRoot::CloneParts(), to centralize
  the part cloning functionality into a single place.
- Replace NodeCloningData's HeapHashMap architecture with a much
  simpler stack architecture. Also eliminate the cloning part queue,
  and replace it with a clone-as-you-go approach. With this new
  system, as a Node containing Parts is cloned, the Parts are
  iterated and cloned, validating them with IsValid first. As
  ChildNodeParts are encountered, they are cloned with both sibling
  nodes pointing to the same node, and the new ChildNodePart is pushed
  onto the part root stack. As the next_sibling is encountered, the
  ChildNodePart is updated to have the correct sibling node, and the
  part root stack is popped. All of this together achieves the same
  behavior, but with much lower speed cost.
- Part::IsValid() is cached to improve speed, and disconnected_
  becomes connected_ to avoid a `!`.
- PartRoot's cached parts list is converted from a Deque to a
  HeapVector, which is more efficient. That eliminates the ability
  to modify the front of the list, so this will adversely impact
  performance for some operations when DOMPartsAPIActivePartTracking
  is enabled (off by default).

Bug: 1453291
Change-Id: I2a2025dd4d1e0c1fa4c85a21469526f6ff1f86d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4909445
Reviewed-by: Joey Arhar <jarhar@chromium.org>
Commit-Queue: Mason Freed <masonf@chromium.org>
Auto-Submit: Mason Freed <masonf@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1205329}