RFR: [bworld] javac crash for abstract methods with null restricted arguments

[Vicente Romero]

fixing a silly bug, basically javac can crash for code like:


abstract class I {
    abstract void m(String! s);
}

javac was trying to access the method's body but it is null

TIA

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

Commit messages:
 - minor fix
 - [bworld] javac crash for abstract methods with null restricted arguments

Changes: https://git.openjdk.org/valhalla/pull/2044/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=2044&range=00
  Stats: 30 lines in 2 files changed: 21 ins; 3 del; 6 mod
  Patch: https://git.openjdk.org/valhalla/pull/2044.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/2044/head:pull/2044

PR: https://git.openjdk.org/valhalla/pull/2044