Bug 1776198 - Disable nsImageGeometryMixin. r=aosmond

Now that we always sync decode during reftests we don't switch from non-sync to
sync decoding and expect proper invalidations. For now, we just make sure that
nsImageGeometryMixin never causes invalidations. We'll rip out the code in a
follow up.

Differential Revision: https://phabricator.services.mozilla.com/D150114

layout/painting/nsDisplayListInvalidation.h

@@ -142,7 +142,7 @@ class nsImageGeometryMixin {
       return false;
     }
 
-    return true;
+    return false;
   }
 
  private: