RFR: 8329559: Test javax/swing/JFrame/bug4419914.java failed because The End and Start buttons are not placed correctly and Tab focus does not move as expected [v2]

[Prasanta Sadhukhan]

> Test issue shows the End and Start buttons are not placed as per instructions due to ComponentOrientation RTL was not honoured, as with `getContentPane()` being removed from `add` call of JFrame, it was also additionally removed from other JFrame calls which resulted in the RTL not being propagated to its child. Fix is to add `getContentPane()` to the non-add methods of JFrame as was done in the applet version of the test..

Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:

  instruction formatting

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18612/files
  - new: https://git.openjdk.org/jdk/pull/18612/files/61a0a049..79123987

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18612&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18612&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18612.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18612/head:pull/18612

PR: https://git.openjdk.org/jdk/pull/18612