Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
  *               (http://www.torchmobile.com/)
@@ skipping 612 matching lines @@
   }
   // TODO(crbug.com/365897): we should get rid of detached layout subtrees, at
   // which point this code should not be reached.
   return nullptr;
 }
 
 bool LayoutObject::ScrollRectToVisible(const LayoutRect& rect,
                                        const ScrollAlignment& align_x,
                                        const ScrollAlignment& align_y,
                                        ScrollType scroll_type,
-                                       bool make_visible_in_visual_viewport) {
+                                       bool make_visible_in_visual_viewport,
+                                       ScrollBehavior scroll_behavior) {
   LayoutBox* enclosing_box = this->EnclosingBox();
   if (!enclosing_box)
     return false;
 
   enclosing_box->ScrollRectToVisible(rect, align_x, align_y, scroll_type,
-                                     make_visible_in_visual_viewport);
+                                     make_visible_in_visual_viewport,
+                                     scroll_behavior);
   return true;
 }
 
 LayoutBox* LayoutObject::EnclosingBox() const {
   LayoutObject* curr = const_cast<LayoutObject*>(this);
   while (curr) {
     if (curr->IsBox())
       return ToLayoutBox(curr);
     curr = curr->Parent();
   }
@@ skipping 2996 matching lines @@
     const blink::LayoutObject* root = object1;
     while (root->Parent())
       root = root->Parent();
     root->ShowLayoutTreeAndMark(object1, "*", object2, "-", 0);
   } else {
     WTFLogAlways("%s", "Cannot showLayoutTree. Root is (nil)");
   }
 }
 
 #endif