RFR: 8325690: The scrollable element <div> with non-interactive content is not tabbable [v30]

[psoujany]

> The scrollable element `<div>` with non-interactive content is not tabbable. Grid columns in the javadoc stylesheet has overflow: auto, which is failing Accessibility checks.
> https://bugs.openjdk.org/browse/JDK-8325690

psoujany has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 33 additional commits since the last revision:

 - Merge branch 'openjdk:master' into remove-overflow
 - Add tabindex to tabbable elements
 - Add tabindex to tabbable elements
 - Make only elements which are tabbable
 - Make only elements which are tabbable
 - Merge branch 'openjdk:master' into remove-overflow
 - Add tabindex only to elemetns which are not tabbable
 - Add tab order to plain text
 - Add tab order to plain text
 - Add tabindex to plain text
 - ... and 23 more: https://git.openjdk.org/jdk/compare/1dcf0269...a2055fe2

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/17819/files
  - new: https://git.openjdk.org/jdk/pull/17819/files/265ee868..a2055fe2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17819&range=29
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17819&range=28-29

  Stats: 38971 lines in 940 files changed: 23649 ins; 11991 del; 3331 mod
  Patch: https://git.openjdk.org/jdk/pull/17819.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17819/head:pull/17819

PR: https://git.openjdk.org/jdk/pull/17819