Revert "[a11y] Fixes move by format for CSS spellcheck highlights"

This reverts commit c6bfb8a1557613e66abbf354b8ae12b560070921.

Reason for revert: This change broke Narrator's move-by-headings
feature. Heading navigation is a critical feature of screen readers that
facilites navigating web pages, like the google/bing results page. It
impacts all headings throughout the web, whereas the original CL was
fixing a scoped problem: spelling errors unannounced when exposed using
CSS highlights. We will also revert this change from 134.

Original change's description:
> [a11y] Fixes move by format for CSS spellcheck highlights
>
> Uses Spelling/Grammar error CSS highlight markers in the
> Accessibility Tree to break format boundaries around those
> errors to help navigate better around these spelling/grammar
> errors.
>
> This CL achieves following:
> 1) Fixes Move by format to accommodate CSS spellcheck highlights.
> 2) Narrator calls out the spelling issues correctly.
>
> Bug: 364795299
> Change-Id: I4842a49449c666100e31f859447f951e9f9eb09e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6178990
> Auto-Submit: Vinay Singh <vinaysingh@microsoft.com>
> Reviewed-by: Benjamin Beaudry <benjamin.beaudry@microsoft.com>
> Commit-Queue: Benjamin Beaudry <benjamin.beaudry@microsoft.com>
> Cr-Commit-Position: refs/heads/main@{#1415710}

Bug: 402800783, 364795299
Change-Id: I1ee7bd394f18fba21e97e5cc8998de1a03501931
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6349562
Reviewed-by: Jacques Newman <janewman@microsoft.com>
Auto-Submit: Benjamin Beaudry <benjamin.beaudry@microsoft.com>
Commit-Queue: Benjamin Beaudry <benjamin.beaudry@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1431891}