Fix crash on forwarding messages

onAttachFragment in ForwardMessageActivity does not necessarily have
to be provided with a ConversationListFragment, so there is no need to
assert this. Just move along, as is done in VCardDetailActivity, etc.

Change-Id: I41825c9c118d71d447b820d29f60fb10ef2d5fdf

src/com/android/messaging/ui/conversationlist/ForwardMessageActivity.java

@@ -46,9 +46,10 @@ public class ForwardMessageActivity extends BaseBugleActivity
 
     @Override
     public void onAttachFragment(final Fragment fragment) {
-        Assert.isTrue(fragment instanceof ConversationListFragment);
-        final ConversationListFragment clf = (ConversationListFragment) fragment;
-        clf.setHost(this);
+        if (fragment instanceof ConversationListFragment) {
+            final ConversationListFragment clf = (ConversationListFragment) fragment;
+            clf.setHost(this);
+        }
     }
 
     @Override