RFR: JDK-8308015: Syntax of "import static" is incorrect in com.sun.source.tree.ImportTree.java

[Jonathan Gibbons]

Please review a trivial change to fix a bug in a non-normative part of the spec for `ImportTree`

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

Commit messages:
 - JDK-8308015: Syntax of "import static" is incorrect in com.sun.source.tree.ImportTree.java

Changes: https://git.openjdk.org/jdk/pull/13960/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13960&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8308015
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13960.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13960/head:pull/13960

PR: https://git.openjdk.org/jdk/pull/13960