RFR: 8267374: (macos) Left Option+Up/Down arrow dont traverse to beginning/end of line in textarea [v7]

[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:

  Remove altgraph mapping

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9230/files
  - new: https://git.openjdk.org/jdk/pull/9230/files/a586dd05..3fa91217

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9230&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9230&range=05-06

  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 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