RFR: 8268718: [macos] Video stops, but audio continues to play when stopTime is reached

[Alexander Matveev]

Not sure why, but our finish() handle was not implemented on OSXPlatform. This handle should pause media stream when called. Also, seek should restart playback when we finish playing video. With proposed fix OSXPlatform will behave same as GSTPlatform. Stop playback when stopTime is reached and resume playback if seek is performed after EndOfMedia or stopTime is reached.

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

Commit messages:
 - 8268718: [macos] Video stops, but audio continues to play when stopTime is reached

Changes: https://git.openjdk.java.net/jfx/pull/559/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=559&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268718
  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/559.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/559/head:pull/559

PR: https://git.openjdk.java.net/jfx/pull/559