Clean backport of 8277133: Dragboard contents retrieved all over again during a DND process on WebView
------------- Commit messages: - 8277133: Dragboard contents retrieved all over again during a DND process on WebView Changes: https://git.openjdk.java.net/jfx11u/pull/64/files Webrev: https://webrevs.openjdk.java.net/?repo=jfx11u&pr=64&range=00 Issue: https://bugs.openjdk.java.net/browse/JDK-8277133 Stats: 101 lines in 5 files changed: 91 ins; 0 del; 10 mod Patch: https://git.openjdk.java.net/jfx11u/pull/64.diff Fetch: git fetch https://git.openjdk.java.net/jfx11u pull/64/head:pull/64 PR: https://git.openjdk.java.net/jfx11u/pull/64
