RFR: 8281953: NullPointer in InputMethod components in JFXPanel

[eduardsdv]

If the InputMethod's node is not in the scene, the default text location point is returned.

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Commit messages:
 - 8281953: NullPointer in InputMethod components in JFXPanel

Changes: https://git.openjdk.java.net/jfx/pull/735/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=735&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281953
  Stats: 17 lines in 2 files changed: 16 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/735.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/735/head:pull/735

PR: https://git.openjdk.java.net/jfx/pull/735