[jfx18] RFR: 8278980: Update WebKit to 613.1

[Johan Vos]

Co-authored-by: Ajit Ghaisas <aghaisas at openjdk.org>
Co-authored-by: Jay Bhaskar <jay.bhaskar at oracle.com>
Co-authored-by: Kevin Rushforth <kcr at openjdk.org>
Reviewed-by: kcr, jvos, aghaisas

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Commit messages:
 - 8278980: Update WebKit to 613.1

Changes: https://git.openjdk.java.net/jfx/pull/770/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=770&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278980
  Stats: 412962 lines in 6737 files changed: 231442 ins; 135635 del; 45885 mod
  Patch: https://git.openjdk.java.net/jfx/pull/770.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/770/head:pull/770

PR: https://git.openjdk.java.net/jfx/pull/770