RFR: 8267374: (macos) Left Option+Up/Down arrow dont traverse to beginning/end of line in textarea [v4]

[Prasanta Sadhukhan]

> Unlike in native "Notes" editor where Option+Up/Down traverses to start/end of each line respectively,
> Java does not honour these key combination in editor.
> 
> Added the key combination support by moving the caret to start/end of line and then doing caret up/down a line depending on if we are pressing UP or DOWN key.

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

  Fix Right Option Key handling

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9230/files
  - new: https://git.openjdk.org/jdk/pull/9230/files/0268daed..8149271b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9230&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9230&range=02-03

  Stats: 21 lines in 2 files changed: 20 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9230.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9230/head:pull/9230

PR: https://git.openjdk.org/jdk/pull/9230