Our implementation of the spec got one comparison wrong, at
step 19.d.iii (we were comparing against 'q' instead of 'p').

R=littledan@chromium.org
BUG=chromium:607566
LOG=n

Review-Url: https://codereview.chromium.org/1940643002
Cr-Commit-Position: refs/heads/master@{#35947}