[jfx11u] RFR: 8255940: localStorage is null after window.close()

[Ambarish Rapte]

Reviewed-by: kcr, arapte

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Commit messages:
 - 8255940: localStorage is null after window.close()

Changes: https://git.openjdk.java.net/jfx11u/pull/88/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx11u&pr=88&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255940
  Stats: 168 lines in 4 files changed: 167 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx11u/pull/88.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx11u pull/88/head:pull/88

PR: https://git.openjdk.java.net/jfx11u/pull/88