[iOS] Remove kNonModalDialog check from BrowserContainerViewController.

This is no longer necessary, as OverlayPresentationContextViewController
defines the presentation context for overlay UI presented using
UIModalPresentationOverCurrentContext presentation.

Bug: 1068418
Change-Id: I6909389cdbc6b2abe2a0f01414e823e78e8072fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2140189
Commit-Queue: Kurt Horimoto <kkhorimoto@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757606}

ios/chrome/browser/ui/browser_container/BUILD.gn

@@ -30,7 +30,6 @@ source_set("ui") {
 
   deps = [
     "//base",
-    "//ios/chrome/browser/ui/dialogs:feature_flags",
     "//ios/chrome/browser/ui/util",
   ]
 }

ios/chrome/browser/ui/browser_container/browser_container_view_controller.mm

@@ -5,7 +5,6 @@
 #import "ios/chrome/browser/ui/browser_container/browser_container_view_controller.h"
 
 #include "base/logging.h"
-#import "ios/chrome/browser/ui/dialogs/dialog_features.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -19,9 +18,6 @@
 
 - (void)viewDidLoad {
   [super viewDidLoad];
-
-  self.definesPresentationContext =
-      base::FeatureList::IsEnabled(dialogs::kNonModalDialogs);
   self.view.autoresizingMask =
       UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
 }