8168774: Polymorhic signature method check crashes javac
Summary: Check for polysig method assumes arity is greater than zero
Reviewed-by: vromero
T4720356a.java:16:16: compiler.err.override.incompatible.ret: (compiler.misc.cant.override: m(), p1.T4720356c, m(), p1.T4720356a), int, void
1 error