RFR: 8264952: [TestBug] Controls unit tests - ControlTest and SpinnerTest fail for non US Locale

[Kevin Rushforth]

On Thu, 22 Apr 2021 10:36:40 GMT, Ajit Ghaisas <aghaisas at openjdk.org> wrote:

> This PR fixes controls unit test failures that are observed with German locale.
> 
> Fix :
> Code added to use US locale while running SpinnerTest and DatePicker test & restore locale to default after these tests are executed.
> 
> test.javafx.scene.control.ControlTest.testRT18097 fails for DatePicker control. Fixing DatePickerTest fixes this. This reveals the fact that our unit tests run in a single VM and any test that changes the Locale setting should restore it to the default at the end.

Btw, the test I mentioned above in `javafx.base` is [test.javafx.util.converter.LocalDateTimeStringConverterTest](https://github.com/openjdk/jfx/blob/4a9c8923a8e6e8c7ce01b72971d194c7ba219037/modules/javafx.base/src/test/java/test/javafx/util/converter/LocalDateTimeStringConverterTest.java#L62).

-------------

PR: https://git.openjdk.java.net/jfx/pull/476