RFR: 8377904: Replace Double.parseDouble() with CssNumberParser

[Michael Strauß]

Replace occurrences of `Double.parseDouble()` with `CssNumberParser.parseDouble()` in CSS-related code.

As with #2069, the specification of JavaFX CSS is not changed.

There are no new tests, because the existing tests already cover all affected code paths.

-------------

Commit messages:
 - Replace Double.parseDouble() with CssNumberParser

Changes: https://git.openjdk.org/jfx/pull/2087/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2087&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377904
  Stats: 71 lines in 3 files changed: 34 ins; 11 del; 26 mod
  Patch: https://git.openjdk.org/jfx/pull/2087.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2087/head:pull/2087

PR: https://git.openjdk.org/jfx/pull/2087