RFR: JDK-8290469: Add new positioning options to PassFailJFrame test framework [v6]

[Harshitha Onkar]

> Additional position setting (TOP_LEFT_CORNER) and a method to obtain bounds of test instruction frame are added to PassFailJFrame to handle positioning of multiple test frames.
> 
> In scenarios where multiple test windows might be present, the test windows might overlap the instruction frame. In order to fix this TOP_LEFT_CORNER position option is added that positions the test instruction frame at top left corner with main test window below it.
> 
> Additionally `getInstructionFrameBounds()` is added to obtain the position and dimensions of test instruction frame.

Harshitha Onkar has updated the pull request incrementally with one additional commit since the last revision:

  added null check in positionWindow

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9525/files
  - new: https://git.openjdk.org/jdk/pull/9525/files/195002df..96629ad3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9525&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9525&range=04-05

  Stats: 26 lines in 2 files changed: 12 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/9525.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9525/head:pull/9525

PR: https://git.openjdk.org/jdk/pull/9525