Fix stale vector tile data for tiles that missed dirty regions while not rendered

[danielzhong]

Description

Follow up to #13577.

I noticed that when I zoom the camera in and out, some tiles occasionally disappear and become invisible. However, it doesn't seem to be reproducible for everyone—for example, @donmccurdy couldn't reproduce it on macOS.

Below is a quick suggestion from GitHub Copilot that appears to fix the issue.

Dirty rectangles in VectorProvider are transient, they are recorded during the provider's update() pre-pass, tested against rendered tiles, and cleared by makeClean() at the end of the same frame. A tile that is outside the rendered set never gets a chance to test against them. When that tile later re-enters the rendered set, updateTileData finds no intersecting dirty rectangles and keeps its cached VectorTileData, even though the underlying collections have changed.

Added:

• VectorProvider._changeCount: incremented each time a dirty rectangle is recorded.
• VectorProvider._changeCountAtClean: snapshot taken in makeClean().
• Every VectorTileData is stamped with the current _changeCount when baked, and re-stamped when it passes validation in updateTileData.
• In updateTileData, data stamped before the last clean may have missed dirty regions that were already consumed, so it is released and re-baked. Otherwise the existing dirty-rectangle intersection test applies as before.

Issue number and link

Testing plan

Author checklist

• I have submitted a Contributor License Agreement
  - [ ] I have added my name to CONTRIBUTORS.md
• I have updated CHANGES.md with a short summary of my change
• I have added or updated unit tests to ensure consistent code coverage
• I have updated the inline documentation, and included code examples where relevant
• I have performed a self-review of my code

AI acknowledgment

• I used AI to generate content in this PR
• If yes, I have reviewed the AI-generated content before submitting

If yes, I used the following Tools(s) and/or Service(s):
GitHub Copilot

If yes, I used the following Model(s):
Fable 5.0

[github-actions]

Thank you for the pull request, @danielzhong!

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