Bug 890997 - Enable OMTC on 10.6. r=bgirard

gfx/thebes/gfxPlatformMac.cpp

@@ -429,12 +429,7 @@ 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();
+  return true;
 }
 
 qcms_profile *