Include these property setters.

They are used by animators to adjust list properties during the animation.
The "set" in front is a system convention for looking up property setters
in a class.

Change-Id: Ic09529e5964d2653a1b25d4b66a053bf7efa4930
diff --git a/proguard.flags b/proguard.flags
index 6996693..c3f7930 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -35,3 +35,12 @@
 -keepclasseswithmembers class com.android.mail.ui.ConversationViewFragment$MailJsBridge {
   public <methods>;
 }
+
+-keepclasseswithmembers class com.android.mail.ui.TwoPaneLayout {
+  *** setFoldersLeft(...);
+  *** setListBitmapLeft(...);
+  *** setListBitmapAlpha(...);
+  *** setListLeft(...);
+  *** setListAlpha(...);
+  *** setConversationLeft(...);
+}
\ No newline at end of file