RFR: 8279614: The left line of the TitledBorder is not painted on 150 scale factor [v12]

[Alisen Chung]

> Changed the drawing area to be increased by 0.5 on the left side to prevent clipping

Alisen Chung has updated the pull request incrementally with three additional commits since the last revision:

 - changed error message for gap between highlight and shadow
 - fixed coordinate checks
 - fixed bottom edge border starting x value, updated test

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7449/files
  - new: https://git.openjdk.java.net/jdk/pull/7449/files/a7935828..6767407d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7449&range=11
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7449&range=10-11

  Stats: 169 lines in 2 files changed: 92 ins; 19 del; 58 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7449.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7449/head:pull/7449

PR: https://git.openjdk.java.net/jdk/pull/7449