Display the toolbar when opening new tab on iPad

When the user long press a link and open it in a new tab, the toolbar
should stay in its state on iPhone. On iPad, the toolbar should be
shown.

Bug: 793830
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I34c345ba0687385a6e546181584230631ed61ad3
Reviewed-on: https://chromium-review.googlesource.com/823923Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523738}

ios/chrome/browser/ui/browser_view_controller.mm

@@ -3295,7 +3295,8 @@ bubblePresenterForFeature:(const base::Feature&)feature
     // TODO(crbug.com/778822): This can be cleaned up when the new fullscreen
     // is enabled.
     if (IsSafeAreaCompatibleToolbarEnabled() &&
-        header.view == _toolbarCoordinator.toolbarViewController.view) {
+        header.view == _toolbarCoordinator.toolbarViewController.view &&
+        !IsIPadIdiom()) {
       self.toolbarOffsetConstraint.constant = yOrigin;
     }
     CGRect frame = [header.view frame];