RFR: 6429812: NPE after calling JTable.updateUI() when using a header renderer + XP L&F [v4]

[Tejesh R]

> _Header_ object not initialized/set when paint() method of `WindowTableHeaderUI` class is executed. The paint() event is executed through explicit call of `JTable.updateUI()` in the regression test. In order to set the _header_ to the _called_ JTable, it is set in the `getTableCellRendererComponent()` method, which in turn makes the _header_ object available during paint event without causing NPE.

Tejesh R has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 14 additional commits since the last revision:

 - Updated based on review comments
 - Merge branch 'master' of https://git.openjdk.java.net/jdk into branch_6429812
 - JTREG Tags updation
 - Removal of White space
 - Updated based on review comments and Added Test case TableRenderTest.java
 - header object set
 - Merge remote-tracking branch 'upstream/master' into branch_6429812
 - Merge remote-tracking branch 'upstream/master'
 - Merge branch 'master' of github.com:TejeshR13/jdk
 - Merge branch 'openjdk:master' into master
 - ... and 4 more: https://git.openjdk.java.net/jdk/compare/a89bbd0c...98c2aab2

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8830/files
  - new: https://git.openjdk.java.net/jdk/pull/8830/files/f7b44322..98c2aab2

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8830&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8830&range=02-03

  Stats: 104546 lines in 1509 files changed: 41748 ins; 52654 del; 10144 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8830.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8830/head:pull/8830

PR: https://git.openjdk.java.net/jdk/pull/8830