[RFR][openjfx13] 8227079: Cherry pick GTK WebKit 2.24.3 changes

[Arunprasad Rajkumar]

Hi Kevin, Johan,

Please review the following PR which merges changes from GTK WebKit 2.24.3 
release.

https://github.com/javafxports/openjdk-jfx/pull/515

Thanks,
Arun