[jfx17u] RFR: 8310681: Update WebKit to 616.1

[Johan Vos]

almost clean backport (apart from remove/add FontCustomPlatformData.h) of 8310681: Update WebKit to 616.1 
Reviewed-by: kcr, sykora

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Commit messages:
 - 8310681: Update WebKit to 616.1

Changes: https://git.openjdk.org/jfx17u/pull/134/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx17u&pr=134&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310681
  Stats: 156 lines in 2 files changed: 98 ins; 58 del; 0 mod
  Patch: https://git.openjdk.org/jfx17u/pull/134.diff
  Fetch: git fetch https://git.openjdk.org/jfx17u.git pull/134/head:pull/134

PR: https://git.openjdk.org/jfx17u/pull/134