RFR: 8307799: Newly added java/awt/dnd/MozillaDnDTest.java has invalid jtreg `@requires` clause

[Daniel D. Daugherty]

A trivial fix to adjust an `@requires` tag into the proper format.

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

Commit messages:
 - Fix a bad copy-and-paste.
 - 8307799: Newly added java/awt/dnd/MozillaDnDTest.java has invalid jtreg `@requires` clause

Changes: https://git.openjdk.org/jdk/pull/13906/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13906&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307799
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13906.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13906/head:pull/13906

PR: https://git.openjdk.org/jdk/pull/13906