RFR: 8278620: properties installed by javax.swing.LookAndFeel installColors and installColorsAndFont are not uninstalled

[SWinxy]

Many `installDefaults` methods set the font, foreground, and background on objects but their inverse methods `uninstallDefaults` do not remove them. I've added an inverse method to remove the colors and font to call for the `uninstallDefaults` methods that install defaults.

`AquaButtonUI` can call its super since it would otherwise be repeated code. `BasicComboBoxUI` (weirdly) installs the properties again when it should be uninstalling them, so I changed.

I noticed that, in a few subclasses, only one of calls to the super of `installDefaults` and `uninstallDefaults` are made. That is, an overridden `installDefaults` may call its super while the overridden `uninstallDefaults` does not call its super (or vise versa). These classes are: `AquaTabbedPaneUI`, `SynthMenuItemUI`, `SynthSplitPaneUI`, and `XTextAreaPeer`.

Sorry I couldn't write a test; I wasn't sure how I should have accessed the protected variable aside from creating extending classes for each class that changed.

See also #6603, where this issue was discovered.

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Commit messages:
 - Accidental imports added
 - 8278620: properties installed by javax.swing.LookAndFeel installColors and installColorsAndFont are not uninstalled

Changes: https://git.openjdk.org/jdk/pull/10565/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10565&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8278620
  Stats: 112 lines in 28 files changed: 74 ins; 12 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/10565.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10565/head:pull/10565

PR: https://git.openjdk.org/jdk/pull/10565