RFR: 8291853: [CSS] ClassCastException in CssStyleHelper calculateValue

[Andy Goryachev]

A race condition exists where a derived color depends on another derived color which has not been yet defined or processed.  The only side effect of this condition is a ClassCastException - the color eventually gets resolved.

Solution: initialize the derived color to transparent earlier to suppress the exception.

This was also a test bug https://bugs.openjdk.org/browse/JDK-8198604

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Commit messages:
 - Merge remote-tracking branch 'origin/master' into 8291853.class.cast
 - 8291853: initialize derived color early

Changes: https://git.openjdk.org/jfx/pull/947/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=947&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291853
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/947.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/947/head:pull/947

PR: https://git.openjdk.org/jfx/pull/947