RFR: JDK-8015739: Background of JInternalFrame is located out of JInternalFrame [v9]

[Harshitha Onkar]

> JInternalFrame background color seems to overflow into the border region. This issue is more prominently seen on Windows - Metal LAF (with fractional scaling, as shown below). The primary reason is border scaling issue as observed in - [JDK-8279614](https://bugs.openjdk.org/browse/JDK-8279614) 
> 
> The fix involves a similar approach as described here https://github.com/openjdk/jdk/pull/7449#issuecomment-1068218648. The test checks the midpoint and corners of borders to check if the internal frame's background color is located out of JInternalFrame.
> 
> ![image](https://user-images.githubusercontent.com/95945681/190233555-a7e00f2c-9003-4c11-84fb-207957838c2f.png)

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

  fix for pixel color at edge, outermost border lines drawn as part of bulk of border

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10274/files
  - new: https://git.openjdk.org/jdk/pull/10274/files/2e3b7af1..da54767f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10274&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10274&range=07-08

  Stats: 36 lines in 2 files changed: 1 ins; 20 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/10274.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10274/head:pull/10274

PR: https://git.openjdk.org/jdk/pull/10274