Move the notion of current Tab from TabModel to WebStateList.

ios/chrome/browser/ui/browser_view_controller.mm

Index: ios/chrome/browser/ui/browser_view_controller.mm
diff --git a/ios/chrome/browser/ui/browser_view_controller.mm b/ios/chrome/browser/ui/browser_view_controller.mm
index f7fd1da28719c31c80dccc4808575a1e31435004..83d0400f29f12b5979f0c8376b78a48e3535dd90 100644
--- a/ios/chrome/browser/ui/browser_view_controller.mm
+++ b/ios/chrome/browser/ui/browser_view_controller.mm
@@ -3581,9 +3581,7 @@ class BrowserBookmarkModelBridge : public bookmarks::BookmarkModelObserver {
       // and show the prerendering animation.
       newTab.isPrerenderTab = NO;
 
-      BOOL loadingFinished =
-          [newTab.webController loadPhase] == web::PAGE_LOADED;
-      [self tabLoadComplete:newTab withSuccess:loadingFinished];
+      [self tabLoadComplete:newTab withSuccess:newTab.loadFinished];
 
       return;
     }
@@ -4554,8 +4552,7 @@ class BrowserBookmarkModelBridge : public bookmarks::BookmarkModelObserver {
     newTab.isPrerenderTab = NO;
     [_model setCurrentTab:newTab];
 
-    BOOL loadingFinished = [newTab.webController loadPhase] == web::PAGE_LOADED;
-    if (loadingFinished)
+    if (newTab.loadFinished)
       [self tabLoadComplete:newTab withSuccess:YES];
 
     if (focusInput) {