Update 16-09-19TPAC-1.md

Author: hayatoito

meetings/16-09-19TPAC-1.md

@@ -57,6 +57,7 @@ Dominic (Google): `<button>` produces something that is focusable and has an ARI
   - https://github.com/w3c/webcomponents/issues/78
   - Blink will implement this feature behind a flag to know whether this feature can be justified or not.
     We need feedback from web developers.
+  - Some sites which use Shadow DOM v0 can not switch to Shadow DOM v1 due to the lack of the support of this feature.
 
 - {DocumentOrShadowRoot or Slot}.activePath
   - https://github.com/w3c/webcomponents/issues/479