Fix super nested class bugs (#7691)

* Properly traverse nested class for supers

* Add object nested in class cases

* Add object nested object cases

* Test class properties

* Undo changes to lerna.json

* Add tests arournd prefix/postfix super increment

* tmp

* Use sets

packages/babel-plugin-proposal-class-properties/test/fixtures/nested-class/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["external-helpers", "proposal-class-properties", "transform-classes"]
+}