[jfx11u] RFR: 8268849: Update to 612.1 version of WebKit

[Kevin Rushforth]

On Tue, 17 Aug 2021 17:33:13 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> Nearly clean backport of third-party update to WebKit 612.1. There was one minor conflict in one unit test file due to difference in context.
> 
> As an FYI, I tested this patch in my [test-kcr-11.0.13](https://github.com/kevinrushforth/jfx11u/tree/test-kcr-11.0.13) branch, which has the aggregate set of patches for the following bugs: [JDK-8211308](https://bugs.openjdk.java.net/browse/JDK-8211308), [JDK-8268915](https://bugs.openjdk.java.net/browse/JDK-8268915), [JDK-8269147](https://bugs.openjdk.java.net/browse/JDK-8269147), [JDK-8269131](https://bugs.openjdk.java.net/browse/JDK-8269131), [JDK-8268849](https://bugs.openjdk.java.net/browse/JDK-8268849), [JDK-8270479](https://bugs.openjdk.java.net/browse/JDK-8270479), [JDK-8272329](https://bugs.openjdk.java.net/browse/JDK-8272329).

There are two follow-on issues that depend on this one, each of which has a Draft PR out for review: PR #35 and PR #36. As soon as _this_ PR is ready, I will update those two PRs with the latest master (including the commit for this PR) and make them `rfr`. Since they are clean backports, I will then integrate them right after that.

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PR: https://git.openjdk.java.net/jfx11u/pull/34