Only :host and :ancestor should ever match the host in a ShadowRoot

Only :host and :ancestor should ever match the host in a ShadowRoot

We were blocking tag, id and class from matching when put before :host, but were
not correctly stopping things like :first-child:host or *:host.

Instead of trying to black list selectors we need to whitelist :host and
:ancestor as being special.

It turns out we did have test coverage for this, but the expected results were
all wrong so it printed PASS even though we were failing what the test was
supposed to be testing.

BUG=355149, 355158
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169799

[esprehn, 2014-03-22 02:52:18]

Okay this is ready for review.

[dglazkov, 2014-03-22 15:22:26]

lgtm

[dglazkov, 2014-03-22 15:22:31]

The CQ bit was checked by dglazkov@chromium.org

[commit-bot: I haz the power, 2014-03-22 15:22:37]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/esprehn@chromium.org/208933006/110001

[commit-bot: I haz the power, 2014-03-22 20:57:09]

Change committed as 169799

[esprehn, 2015-01-17 01:05:28]

Patchset #8 (id:120001) has been deleted