Keep looking for allowed punctuation when punctuation that precedes the first letter is already found.

We keep looking for whitespace and allowed punctuation in order to find close punctuation
after checking first letter, but we need to do this when there is any punctuation
that precedes the first letter.

BUG=61724
TEST=fast/css/first-letter-punctuation-follow.html

Review URL: https://codereview.chromium.org/27321003

git-svn-id: svn://svn.chromium.org/blink/trunk@161910 bbb929c8-8fbe-4397-9dbb-9b2b20218538