[ios] Fix ui refresh rtl tab strip counter.

Continue to use old-school layout logic in tab strip.

Bug: 843249
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I475fda4628f6daa68fc030c93151876e42db1531
Reviewed-on: https://chromium-review.googlesource.com/1063148Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560665}

ios/chrome/browser/ui/tabs/tab_strip_controller.mm

@@ -1149,6 +1149,8 @@ NSString* StringForItemCount(long count) {
   if (IsUIRefreshPhase1Enabled()) {
     _tabSwitcherButton =
         [TabStripCenteredButton buttonWithType:UIButtonTypeCustom];
+    if (UseRTLLayout())
+      [_tabSwitcherButton setTransform:CGAffineTransformMakeScale(-1, 1)];
   } else {
     _tabSwitcherButton = [UIButton buttonWithType:UIButtonTypeCustom];
   }