<AWT Dev> RFR: 8266079: Lanai: AlphaComposite shows differences on Metal compared to OpenGL [v3]

[Alexey Ushakov]

> Keep MTLLayer opacity in sync with window content view
> Keep layer translucent for translucent windows

Alexey Ushakov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  8266079: Lanai: AlphaComposite shows differences on Metal compared to OpenGL
  
  Keep MTLLayer opacity in sync with window content view
  Keep layer translucent for translucent windows
  Update opacity on textured property change
  Make native MTLLayer opaque by default to match java component state

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Changes: https://git.openjdk.java.net/jdk/pull/4946/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4946&range=02
  Stats: 274 lines in 7 files changed: 269 ins; 1 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4946.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4946/head:pull/4946

PR: https://git.openjdk.java.net/jdk/pull/4946