Revert 167914 "DevTools: Replace Apple styled spinner icon with ..."

May have caused timeouts on layout test debug canaries.

> DevTools: Replace Apple styled spinner icon with Chromium one.
> 
> Drive-by: replace animated PNG files with a CSS animation.
> 
> R=yurys@chromium.org
> 
> Review URL: https://codereview.chromium.org/181433002

TBR=alph@chromium.org



git-svn-id: svn://svn.chromium.org/blink/trunk@167947 bbb929c8-8fbe-4397-9dbb-9b2b20218538