We report the byte offset as column number, but devtools assumes them
to be 1-based and subtracts one unconditionally before further
processing it. It's a bit unfortunate, but because of that we have to
just add 1 to the reported column number on the public StackTrace API.

R=ahaas@chromium.org, titzer@chromium.org
BUG=chromium:613110

Review-Url: https://codereview.chromium.org/2071563002
Cr-Commit-Position: refs/heads/master@{#37036}