RFR: 8378359: Remove unused local variable in ViewContainer::HandleViewMouseEvent

[Michael Strauß]

Remove an unused local variable in `ViewContainer::HandleViewMouseEvent`.
A single reviewer is sufficient.

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Commit messages:
 - Remove unused local variable

Changes: https://git.openjdk.org/jfx/pull/2081/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=2081&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8378359
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jfx/pull/2081.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/2081/head:pull/2081

PR: https://git.openjdk.org/jfx/pull/2081