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 ff16f20edcffdd3aa34564354b8ddd79c237ff73..f2d33e4330aca345523988e113e9fbcc2187630b 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -644,13 +644,15 @@ 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;
 }