RFR: 8190264: JScrollBar ignores its border when using macOS Mac OS X Aqua look and feel [v7]

[Alisen Chung]

> Adjusted the AquaLF scrollbar to account for border inset settings when dragging the thumb and clicking on the track.

Alisen Chung has updated the pull request incrementally with one additional commit since the last revision:

  removed robot mouse moves, use pixel colors to check

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6374/files
  - new: https://git.openjdk.java.net/jdk/pull/6374/files/02ae001c..52edbf4e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6374&range=06
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6374&range=05-06

  Stats: 29 lines in 1 file changed: 6 ins; 20 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6374.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6374/head:pull/6374

PR: https://git.openjdk.java.net/jdk/pull/6374