Fix singleton method prefixes

[viralpraxis]

In case of something like

class A
  class << self
    def foo = ??
  end
end

the prefixed name of the foo method is s(:self).foo, not self.foo.

Looks like ideally it should be A.foo (?), but this patch does not address that.

Here's how it looks in the report,

before:

"location": {
  "type": "method",
  "class": "SomeModule::SomeClass",
  "method": "s(:self).some_singleton_method"
}

after:

"location": {
  "type": "method",
  "class": "SomeModule::SomeClass",
  "method": "self.some_singleton_method"
}

[presidentbeef]

I think this won't work if src[1] is not self.

E.g.

def A.foo
  # ...
end

src[1].value might work better (I haven't tested thoroughly).

[viralpraxis]

Hey @presidentbeef,

I think this won't work if src[1] is not self.

Good point. I've added some tests for def Const.m, def @ivar.m and def lvar.m

src[1].value might work better (I haven't tested thoroughly).

It does not work with self (s(:self).value => nil), so I tried another approach. LKM what you think