RFR: 8169187: [macosx] Aqua: java/awt/image/multiresolution/MultiresolutionIconTest.java

[Alisen Chung]

Removed darkening of icons on button press in Aqua to match other L&Fs. The icon darkening was causing this test to fail on MacOS.

The test is passing on all platforms after this change.

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Commit messages:
 - removed darkening of icons on button press in Aqua, workaround robot getPixel on cursor bug in test

Changes: https://git.openjdk.org/jdk/pull/9436/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9436&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8169187
  Stats: 16 lines in 3 files changed: 8 ins; 6 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/9436.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9436/head:pull/9436

PR: https://git.openjdk.org/jdk/pull/9436