GitLab

A third go at https://crrev.com/3c64df1fc98aa06eabfc18d1f5c2f2b0aec1a658

Although I still can't reproduce the clusterfuzz reports locally I'm confident
this will cure the specific crashes because I'm no longer transforming the
first line's text unless it has a distinct first-line style (:/).

BUG=129669,644733

Review-Url: https://codereview.chromium.org/2339683004
Cr-Commit-Position: refs/heads/master@{#418840}