Bubble collapse.

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -2274,6 +2274,14 @@ typedef enum : NSUInteger {
 
 - (void)scrollDownButtonTapped
 {
+#ifdef DEBUG
+    CGPoint contentOffset = self.collectionView.contentOffset;
+    contentOffset.y += self.collectionView.height
+        - (self.collectionView.contentInset.top + self.collectionView.contentInset.bottom);
+    [self.collectionView setContentOffset:contentOffset animated:NO];
+    return;
+#endif
+
     NSIndexPath *indexPathOfUnreadMessagesIndicator = [self indexPathOfUnreadMessagesIndicator];
     if (indexPathOfUnreadMessagesIndicator != nil) {
         NSInteger unreadRow = indexPathOfUnreadMessagesIndicator.row;