fix: correct FLIP animations in scaled parent

[simeydotme]

The issue #7205 describes how FLIP animations occurring inside a parent with transform: scale(n) are wonky, this PR resolves that issue by;

• Geting the scale factor by comparing against node.clientWidth
• Dividing all the positions/dimensions by the scale to get the correct deltas

---

Before submitting the PR, please make sure you do the following

• It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• Prefix your PR title with [feat], [fix], [chore], or [docs].
• This message body should clearly illustrate what problems it solves.

Tests

• Run the tests with npm test and lint the project with npm run lint
• Ideally, include a test that fails without this PR but passes with it.

(I haven't added a test, as I don't really understand how the animate tests are working, and I couldn't find an example in the #6658 commit which caused this regression. If anyone wants to walk me through creating a test, or help append a test to this PR, please let me know! :))

---

• resolves FLIP Animations inside a Scaled Parent are calculated incorrectly #7205
• fixes regression from [fix] better flip animation #6658

[simeydotme]

looks like one test took too long to execute... can't find a "retry" button :/

[simeydotme]

I rebased to try and trigger the CI again, as last time it timed-out on an osx test, and I couldn't re-run the tests ... and I wondered if the failed CI meant the PR would be glossed over during review :)

[simeydotme]

oh cool the checks pass now... I guess the failing tests were fixed in main :)

[Rich-Harris]

Thank you for the fix — unfortunately this got out of date as the flip function was updated for Svelte 5, and the changes don't directly translate (pun intended). I've opened #14957 instead