Bulk request to backport 9 fixes to 11-dev for 11.0.10

[Kevin Rushforth]

Hi Johan,

I request approval to backport the following 9 bug fixes to 11-dev for 
11.0.10:

JDK-8254100: FX: Update copyright year in docs, readme files to 2021
JDK-8251241: macOS: iconify property doesn't change after minimize when 
resizable is false
JDK-8252060: gstreamer fails to build with gcc 10
JDK-8181775: JavaFX WebView does not calculate border-radius properly
JDK-8251858: Update to Xcode 11.3.1
JDK-8252062: WebKit build fails with recent VS 2019 compiler
JDK-8240499: Enforce whitespace checking for additional source files
JDK-8252191: Update to gcc 10.2 on Linux
JDK-8239822: Intermittent unit test failures in RegionCSSTest

-- Kevin