Version:  54.0.2806.0
OS: Ubuntu 14.04,Windows

What steps will reproduce the problem?
(1)Launch Chrome -> Go to chrome://history page
(2)Now Right Click on 'More Actions' Icon and select 'Inspect' option to open Dev Tools window 
(3)Now in Elements Tab click on option "paper-icon-button-light" (Please refer Video)-> Now go to computed Section -> Hover the Mouse at the space which is available at bottom of Vertical scroll bar and observe 

Expected: Unwanted Horizontal scroll bar should not be seen in computed Section of Dev Tools
Actual: Instead Unwanted Horizontal scroll bar is seen  

Note: Horizontal scroll bar is not seen On Mouse Hovering of any option in computed Section 

This is Regression Issue broken in M-54
Manual good and Bad Builds:
Good Build: 54.0.2804.0
Bad Build:  54.0.2805.0

Below is the Tool Bisect Info:

CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/f2e8191e41dae27a051bc54271fbd971db1bfafd..377a9762958c69dba606bfd8dd4b766aad69c9c4

Suspecting https://codereview.chromium.org/2175903002 from changelog

@pfeldman : Please feel free to re-assign if its not related to your change

 

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	Actual_Scrolbar.ogv 1.9 MB View Download

Deleted: Actual_Scrollbar.png 215 KB

	Actual_Scrollbar.png 215 KB View Download

Deleted: Expected_section.ogv 1.3 MB

	Expected_section.ogv 1.3 MB View Download