[sdk] Restrict ownership of Topaz.

This allows the contents of the Dart additions to the Core SDK to be put
under stricter control.

Bug: DX-1200
Change-Id: Ie80f9ba9e87578f6e23db7e375e0270346e8e316
diff --git a/OWNERS b/OWNERS
index f641901..21d4a45 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,4 +1,3 @@
 anwilson@google.com
 chaselatta@google.com
 jasoncampbell@google.com
-*
diff --git a/public/sdk/OWNERS b/public/sdk/OWNERS
index 7667a70..210bc29 100644
--- a/public/sdk/OWNERS
+++ b/public/sdk/OWNERS
@@ -1,3 +1,2 @@
 jinwoo@google.com
 pylaligand@google.com
-*