RFR: 8300872: WebView's ColorChooser fails to initialize when running in security context [v2]

[Jose Pereda]

> This PR removes an unnecessary check that was added as part of [JDK-8267551](https://bugs.openjdk.org/browse/JDK-8267551).
> 
> As commented in the [issue](https://bugs.openjdk.org/browse/JDK-8300872), there were no failing/passing tests before/after these lines were added, and there are no actual tests that get into the case.
> 
> The mentioned check caused, as a side effect, the JDK-8300872 issue, as running under a (deprecated) security manager fails with:
> 
> java.security.AccessControlException: access denied ("java.io.FilePermission" "jrt:/javafx.controls/com/sun/javafx/scene/control/skin/modena/pattern-transparent.png" "read")
> ...
> at javafx.graphics/javafx.scene.image.Image.validateUrl(Image.java:1127)
> ...
> 
> when `File::exists` is evaluated over an image bundled in a jar.

Jose Pereda has updated the pull request incrementally with one additional commit since the last revision:

  Add system test

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1042/files
  - new: https://git.openjdk.org/jfx/pull/1042/files/1cc9c761..ba7aef23

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1042&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1042&range=00-01

  Stats: 199 lines in 4 files changed: 194 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jfx/pull/1042.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1042/head:pull/1042

PR: https://git.openjdk.org/jfx/pull/1042