Google Chrome	60.0.3080.5 (Official Build) dev (64-bit)
Revision	983263d7309ff4e4e9c641874f1e9e0909cdecb3-refs/branch-heads/3080@{#6}
OS	Mac OS X

What steps will reproduce the problem?
(1) Go to facebook.com
(2) Open Devtools
(3) Open Tracing, select manual, All, then click record.

Lots of warnings at the top.

...
Import Warning: UserModelBuilder: Please file a bug with this trace: double-handled event:MouseLeave@33985.994000000064