Revert of Gardening: mark virtual/softwarecompositing as Timeout on Mac (https://codereview.chromium.org/293373002/)

Reason for revert:
272636 has been reverted. in general the tests should not timeout anymore.

Original issue's description:
> Gardening: mark virtual/softwarecompositing as Timeout on Mac
> 
> BUG=377145
> TBR=kbr
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=174755

TBR=
NOTREECHECKS=true
NOTRY=true
BUG=377145

Review URL: https://codereview.chromium.org/297213002

git-svn-id: svn://svn.chromium.org/blink/trunk@174762 bbb929c8-8fbe-4397-9dbb-9b2b20218538