Remove impossible conditions from SelectorChecker::checkOne()

Remove impossible conditions from SelectorChecker::checkOne(). The code is in
an if "(selector.m_match == CSSSelector::PseudoClass)" check scope so it is
impossible for "selector.m_match == CSSSelector::Tag" to ever be true in
the two conditions that are removed.

This is based the following WebKit revision by benjamin@webkit.org:
http://trac.webkit.org/changeset/156380

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/328443003

git-svn-id: svn://svn.chromium.org/blink/trunk@175839 bbb929c8-8fbe-4397-9dbb-9b2b20218538