[ios] Close All in regular tabs also closes incognito tabs

Bug: 825888
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: Ib47af308aef7797fd682f647e8cfa7481c466a0f
Reviewed-on: https://chromium-review.googlesource.com/999306Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: edchin <edchin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548856}

ios/chrome/browser/ui/tab_grid/tab_grid_view_controller.mm

@@ -723,6 +723,7 @@ TabGridPage GetPageFromScrollView(UIScrollView* scrollView) {
       [self.incognitoTabsDelegate closeAllItems];
       break;
     case TabGridPageRegularTabs:
+      [self.incognitoTabsDelegate closeAllItems];
       [self.regularTabsDelegate closeAllItems];
       break;
     case TabGridPageRemoteTabs: