Bug 890997 - Enable OMTC on 10.6. r=bgirard

gfx/thebes/gfxPlatformMac.cpp

@@ -429,13 +429,8 @@ gfxPlatformMac::UseAcceleratedCanvas()
 bool
 gfxPlatformMac::SupportsOffMainThreadCompositing()
 {
-  // 10.6.X has crashes on tinderbox with OMTC, so disable it
-  // for now.
-  if (OSXVersion() >= 0x1070) {
   return true;
 }
-  return GetPrefLayersOffMainThreadCompositionForceEnabled();
-}
 
 qcms_profile *
 gfxPlatformMac::GetPlatformCMSOutputProfile()