RFR: 8302558: Editable JComboBox 's popup blocks user from seeing characters in Acq look and feel

[Damon Nguyen]

The issue is in Aqua L&F when an editable JComboBox with a border is used. In this case, when the comboBox is clicked for the drop-down menu to show, the drop-down menu appears at the wrong coordinates (blocking the text of the comboBox and making it unreadable).

This seems to have been the case for a while and a similar issue appeared recently where an editable Aqua JComboBox also had wrong positioning due to having a border.

This fix checks for a border and modifies the bounds to accommodate the border's size. Then the usual calculations for the comboBox popup works as expected.

The new headful test creates an editable comboBox with a TitledBorder and with no border. Then, it automatically clicks the comboBox to open the popup, and clicks where the position of the first selectionItem should be. Finally, it checks if the selected item is correct. This is for all L&F's and the test passes on all OS's.

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Commit messages:
 - Fix whitespace error
 - Add automated headful test for fix.
 - Update copyright year
 - Modify bounds for border insets

Changes: https://git.openjdk.org/jdk/pull/12750/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12750&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302558
  Stats: 147 lines in 2 files changed: 145 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12750.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12750/head:pull/12750

PR: https://git.openjdk.org/jdk/pull/12750