[jfx17u] RFR: 8268849: Update to 612.1 version of WebKit

[Kevin Rushforth]

Clean backport to `jfx17u`. This has been tested on all platforms along with other pending fixes in the `test-kcr-17.0.1` branch.

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Commit messages:
 - 8268849: Update to 612.1 version of WebKit

Changes: https://git.openjdk.java.net/jfx17u/pull/3/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx17u&pr=3&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268849
  Stats: 286061 lines in 5711 files changed: 175196 ins; 68118 del; 42747 mod
  Patch: https://git.openjdk.java.net/jfx17u/pull/3.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx17u pull/3/head:pull/3

PR: https://git.openjdk.java.net/jfx17u/pull/3