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 ac03b02a63fada3e05335e07899878a16129e44e..fec2f51050c5e5e798d83191e4eacaa1278df9f2 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -633,13 +633,15 @@ bool LayoutObject::scrollRectToVisible(const LayoutRect& rect,
                                        const ScrollAlignment& alignX,
                                        const ScrollAlignment& alignY,
                                        ScrollType scrollType,
-                                       bool makeVisibleInVisualViewport) {
+                                       bool makeVisibleInVisualViewport,
+                                       ScrollBehavior scrollBehavior) {
   LayoutBox* enclosingBox = this->enclosingBox();
   if (!enclosingBox)
     return false;
 
   enclosingBox->scrollRectToVisible(rect, alignX, alignY, scrollType,
-                                    makeVisibleInVisualViewport);
+                                    makeVisibleInVisualViewport,
+                                    scrollBehavior);
   return true;
 }