RFR: 8261460: Incorrect CSS applied to ContextMenu on DialogPane

[Abhinay Agarwal]

Both DialogPane and ContextMenu have a child node with a style-class `graphic-container`. This leads to a corner case where an unwanted style is applied to ContextMenu when it is shown on a DialogPane.

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

Commit messages:
 - Remove executable flag from image and move it to correct directory
 - Remove whitespace
 - Update tests
 - 8261460: Incorrect CSS applied to ContextMenu on DialogPane

Changes: https://git.openjdk.java.net/jfx/pull/400/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=400&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261460
  Stats: 107 lines in 4 files changed: 106 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/400.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/400/head:pull/400

PR: https://git.openjdk.java.net/jfx/pull/400