This PR changes the way `Store.squashHistoryEntries` works. Previously,
the function would iterate through every entry and squash it against the
current entry (using `squashRecordDiffs`) to get the new current entry.
However, `squashRecordDiffs` does basically the same pattern, iterating
through the properties of every diff. As a result, each diff would be
iterated through twice: once as itself, and once again in the next
current.
This PR tweaks the function to operate on as many diffs as possible at
once.
### Change Type
<!-- ❗ Please select a 'Scope' label ❗️ -->
- [x] `sdk` — Changes the tldraw SDK
- [ ] `dotcom` — Changes the tldraw.com web app
- [ ] `docs` — Changes to the documentation, examples, or templates.
- [ ] `vs code` — Changes to the vscode plugin
- [ ] `internal` — Does not affect user-facing stuff
<!-- ❗ Please select a 'Type' label ❗️ -->
- [ ] `bugfix` — Bug fix
- [ ] `feature` — New feature
- [x] `improvement` — Improving existing features
- [ ] `chore` — Updating dependencies, other boring stuff
- [ ] `galaxy brain` — Architectural changes
- [ ] `tests` — Changes to any test code
- [ ] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
- [ ] `dunno` — I don't know
### Test Plan
- [x] Unit Tests
- [ ] End to end tests
### Release Notes
- Minor improvement when modifying multiple shapes at once.
72ae8ddefd