RFR: 8307299: Move more DnD tests to open [v4]

[Alisen Chung]

> Added DnD tests

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

  fix space, add method on EDT

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/13759/files
  - new: https://git.openjdk.org/jdk/pull/13759/files/09ceaf0a..0f5df266

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13759&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13759&range=02-03

  Stats: 7 lines in 3 files changed: 3 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/13759.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13759/head:pull/13759

PR: https://git.openjdk.org/jdk/pull/13759