RFR: 8089913: CSS styling problem with Slider pseudo classes [v2]

[mstr2]

> The Slider control does not have the ":horizontal" CSS pseudo-class set by default. The pseudo-class is only set once the "orientation" property is changed. This PR fixes that.

mstr2 has updated the pull request incrementally with one additional commit since the last revision:

  Empty commit to trigger tests

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/413/files
  - new: https://git.openjdk.java.net/jfx/pull/413/files/12714b01..dfe577cd

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=413&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=413&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/413.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/413/head:pull/413

PR: https://git.openjdk.java.net/jfx/pull/413