RFR: 8296589: PixelBufferDrawTest fails on some systems

[Lukasz Kostyra]

Issue happening on some hardware due to slightly different pixel values being returned.

Increased tolerance of asserts in compareColor function to allow these tests to pass (0.01 delta is still tighter than other similar tests which use 0.07).

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Commit messages:
 - 8296589: PixelBufferDrawTest fails on some systems

Changes: https://git.openjdk.org/jfx/pull/944/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=944&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296589
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/944.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/944/head:pull/944

PR: https://git.openjdk.org/jfx/pull/944