RFR: JDK-8272392 Lanai: SwingSet2. Black background on expanding tree node

[Alexey Ushakov]

Handled SRC composite mode in MTLBlitLoops_IsoBlit

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Commit messages:
 - JDK-8272392 Lanai: SwingSet2. Black background on expanding tree node

Changes: https://git.openjdk.java.net/jdk/pull/5882/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5882&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272392
  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5882.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5882/head:pull/5882

PR: https://git.openjdk.java.net/jdk/pull/5882