Revert of DevTools: fix styles for glasspane (patchset #3 id:40001 of https://codereview.chromium.org/659043002/)

Reason for revert:
A better solution has been landed in https://src.chromium.org/viewvc/blink?view=rev&revision=183868

Original issue's description:
> DevTools: fix styles for glasspane
> 
> The glasspane should be a component-root so that it inherits all the
> basic styling.
> 
> R=pfeldman
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=183813

TBR=pfeldman@chromium.org,lushnikov@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/643773003

git-svn-id: svn://svn.chromium.org/blink/trunk@183869 bbb929c8-8fbe-4397-9dbb-9b2b20218538