Replaced casting with ObjCCastStrict<> to avoid crashes.

ObjCCastStrict<> returns nil if the object being casted is not of the
expected type. This offers a saner behavior when for whatever reasons
object is not of the expected type.

This is a workaround to avoid a growing crash in iOS 11.3 when an
object of UIView type is casted to one of CardView type. A later call
to -closeButtonFrame results in an exception (crash).

Bug: 393230
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I6a3f2b66c4ab6a8f268743e1ce8c902ccffaaa05
Reviewed-on: https://chromium-review.googlesource.com/1005562
Commit-Queue: Peter Lee <pkl@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549688}

ios/chrome/browser/ui/stack_view/stack_view_controller.mm

@@ -2292,8 +2292,11 @@ NSString* const kTransitionToolbarAnimationKey =
     cardView = card.view;
   } else {
     // The recognizer is one of those attached to the card.
-    DCHECK([recognizer.view isKindOfClass:[CardView class]]);
-    cardView = (CardView*)recognizer.view;
+    // See https://crbug.com/393230 where recognizer.view may not be a CardView
+    // type. In that case, early return with a NO to avoid unnecessary crash.
+    cardView = base::mac::ObjCCastStrict<CardView>(recognizer.view);
+    if (!cardView)
+      return NO;
     card = [self cardForView:cardView];
   }