Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
index 769acc39df44b05836e2d8ab1259afcd765a904f..8ba979bf160eee9cb571887c516ed564e0457e75 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -255,7 +255,8 @@ void ScrollableArea::UserScrollHelper(const ScrollOffset& offset,
 LayoutRect ScrollableArea::ScrollIntoView(const LayoutRect& rect_in_content,
                                           const ScrollAlignment& align_x,
                                           const ScrollAlignment& align_y,
-                                          ScrollType) {
+                                          ScrollType,
+                                          bool is_smooth) {
   // TODO(bokan): This should really be implemented here but ScrollAlignment is
   // in Core which is a dependency violation.
   NOTREACHED();