RFR: 8289539: The color returned by CheckBox.interiorBackground is incorrect

[Tejesh R]

The color returned for `InteriorBackground` property is the default color used for only _WindowsClassicLookAndFeel_. For _WindowsLookAndFeel_ the `InteriorBackground` color is not been used when checkbox paint happens. In _WindowsLookAndFeel_ the CheckBox check/uncheck is drawn using `ImageCache` which is totally independent of `InteriorBackground` color in which the user expects it to be.
The proposed fix is to return null for _WindowsLookAndFeel_ (which is what happens in other LookAndFeel like Metal/Synth/Motif/Aqua ) and return default color which is the actual color used in _WindowsClassicLookAndFeel_.

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Commit messages:
 - New line added at end of test case
 - Added Test case
 - Initial Test Fix
 - Merge remote-tracking branch 'upstream/master'
 - Merge remote-tracking branch 'upstream/master'
 - Merge remote-tracking branch 'upstream/master'
 - Merge remote-tracking branch 'upstream/master'
 - Merge remote-tracking branch 'upstream/master'
 - Merge branch 'master' of github.com:TejeshR13/jdk
 - Merge branch 'openjdk:master' into master
 - ... and 4 more: https://git.openjdk.org/jdk/compare/77398430...ff011fb2

Changes: https://git.openjdk.org/jdk/pull/10385/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10385&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289539
  Stats: 75 lines in 2 files changed: 74 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10385.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10385/head:pull/10385

PR: https://git.openjdk.org/jdk/pull/10385