We should never allow reprojecting the inside of author shadows, except when they're
being projected between ShadowRoots of the same type. This breaks all the tests that
were testing what happens if we allowed ShadowRoot on form controls and reproject
the inside of the form control, but we don't actually plan to ship that feature anyway.

I removed all the tests that can't be made into ref tests easily since the result is
a strangely busted form control and updated the other tests to show the behavior
when you add a ShadowRoot to something with author shadows.

This behavior was blocking landing a patch to remove fixPlaceholderRenderer
https://codereview.chromium.org/23035007/ which was further blocking making everything
lazyAttach.

BUG=234020, 253801, 276689

Review URL: https://chromiumcodereview.appspot.com/22852020

git-svn-id: svn://svn.chromium.org/blink/trunk@156668 bbb929c8-8fbe-4397-9dbb-9b2b20218538