RFR: 8307297: Move some DnD tests to open [v2]

[Alisen Chung]

> Adding some DnD tests

Alisen Chung has updated the pull request incrementally with one additional commit since the last revision:

  added space after if, moved some function calls on EDT

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13756/files
  - new: https://git.openjdk.org/jdk/pull/13756/files/7b6e1703..c2451e28

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13756&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13756&range=00-01

  Stats: 14 lines in 2 files changed: 9 ins; 0 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/13756.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13756/head:pull/13756

PR: https://git.openjdk.org/jdk/pull/13756