+rob.buis@, you own the  bug 646133  which is probably related; do you think this is a duplicate? Different OSes, but both fail only on Debug, so it's likely the same core issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/215f64a3800b25e7751303dc956d9d608fdb5a96

commit 215f64a3800b25e7751303dc956d9d608fdb5a96
Author: msramek <msramek@chromium.org>
Date: Fri Nov 18 14:39:03 2016

Disable unitless-length.html on Webkit Linux Trusty (Debug)

imported/wpt/quirks-mode/unitless-length.html is timing out on the Webkit
Linux Trusty (Debug) bot.

NOTRY=true
TBR=rob.buis@samsung.com
BUG= 666712 

Review-Url: https://codereview.chromium.org/2517563002
Cr-Commit-Position: refs/heads/master@{#433194}

[modify] https://crrev.com/215f64a3800b25e7751303dc956d9d608fdb5a96/third_party/WebKit/LayoutTests/TestExpectations

good catch, we might as well dupe these