Pseudo element selectors in compound selector lists are invalid.
These selectors were never matching, but they are invalid and rules with
invalid selectors should not show up in the CSSOM.
This is just partly fixing detection of invalid use of pseudo elements.
We also incorrectly accept simple selectors following pseudo elements.
In most cases those are invalid selectors.
The modified existing cases contained invalid selectors and they were
modified to make them valid for serialization testing purposes.
R=timloh@chromium.org
BUG=489481,393490
Review URL: https://codereview.chromium.org/1576553002
Cr-Commit-Position: refs/heads/master@{#368823}
8 files changed
