CL at https://chromium-review.googlesource.com/c/chromium/src/+/783818.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/96d5ba4896cb76a6d1f09f4e557b45da41eec214

commit 96d5ba4896cb76a6d1f09f4e557b45da41eec214
Author: dpapad <dpapad@chromium.org>
Date: Wed Nov 22 22:25:53 2017

MD Extensions polish: Fix cr-tooltip-icon width/height.

Previously the iron-icon ended up being 20x24 instead of 20x20,
because 20px width/height was applied to the parent cr-tooltip-icon,
instead of applying it on the iron-icon itself.

Bug:  787214 , 787210 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I6154bf0d75fca6bd07703ae17837af2a977b896e
Reviewed-on: https://chromium-review.googlesource.com/783818
Reviewed-by: Dan Beam (no longer on Chrome) <dbeam@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#518772}
[modify] https://crrev.com/96d5ba4896cb76a6d1f09f4e557b45da41eec214/ui/webui/resources/cr_elements/policy/cr_tooltip_icon.html