GROOVY-5875: Cannot use DELEGATE_FIRST and delegates that are inner clas...

...ses.

As described in GROOVY-5875, this patch fixes an edge-case where a static inner class is used as delegate object on a closure. As the accessed property is not found in the inner class, the propertyMissing implementation from the inner class jumps in (it is added by InnerClassCompletionVisitor#addDefaultMethods) and triggers a MissingFieldException and the resolve mechanism breaks.

Please review this pull request carefully, as it patches the behaviour of Closure#getPropertyTryThese.