Backport JDK-8058779 to JDK 8 (faster String.replace(CharSequence, CharSequence))

[Zheka Kozlov]

Hello, guys!

Is there any reason to not backport JDK-8058779
<https://bugs.openjdk.java.net/browse/JDK-8058779> to JDK 8? The JDK 9
implementation is very simple and it's fully localized in the method, so
it's just a matter of a simple copy-paste. According to these
benchmarks, it's ~3 times faster:
https://stackoverflow.com/a/58199878/706317

There is still a huge amount of Java 8 code which would highly benefit from
such backport.

With best regards.

Zheka Kozlov.