core-localstorage, core-selector, and core-selection tests

This PR contains all remaining tests to port from https://github.com/Polymer/core-tests
(they are not many)

Not all tests are working yet
see commit messages for more details

related to #41 

I try to come up with some additional tests.
minor nit: let's add your name/username in the TODO like:

```// TODO(zoechi): ...```

We do this just to make it easier to remember who discovered the problem, so if we have questions we know who to ask :-)