Implement Element.scrollIntoView for scroll-behavior: smooth.

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

Index: third_party/WebKit/Source/core/layout/LayoutObject.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutObject.cpp b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
index adc7d6f538689fc9e5e10004261cb65b56b69546..fe2caf351311a479343e8226511d04609bb3073f 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -631,13 +631,15 @@ 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;
 }