Adapt inner-class-could-be-static query now that specialised methods are callable via an implicit this qualifier.

Previously such a call always targeted the unbound method, so we checked for an inherited method that could be a specialisation thereof; now we expect it should be directly inherited.

java/ql/src/Performance/InnerClassCouldBeStatic.ql

@@ -78,7 +78,7 @@ RefType enclosingInstanceAccess(Expr expr) {
       result = ma.getMethod().getDeclaringType() and
       not exists(ma.getQualifier()) and
       not ma.getMethod().isStatic() and
-      not exists(Method m | m.getSourceDeclaration() = ma.getMethod() | enclosing.inherits(m))
+      not enclosing.inherits(ma.getMethod())
     )
   )
 }