[jfx11u] RFR: 8211308: Support HTTP/2 in WebView

[Kevin Rushforth]

On Tue, 17 Aug 2021 17:13:36 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> Clean backport of HTTP/2. This is enabled by default only with running with JDK 12 or later.
> 
> I have tested this with both JDK 11, where I verified that it HTTP/2 is not enabled, and JDK 15, where I verified that it HTTP/2 is enabled.
> 
> 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).

@johanvos Did you want to review this before I integrate it?

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PR: https://git.openjdk.java.net/jfx11u/pull/30