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 0e1681ef3de8de68557b632c4ba6cd0f38871993..ef5b686833a9a7459701cf25735b7db637200e90 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -249,7 +249,8 @@ void ScrollableArea::userScrollHelper(const ScrollOffset& offset,
 LayoutRect ScrollableArea::scrollIntoView(const LayoutRect& rectInContent,
                                           const ScrollAlignment& alignX,
                                           const ScrollAlignment& alignY,
-                                          ScrollType) {
+                                          ScrollType,
+                                          ScrollBehavior) {
   // TODO(bokan): This should really be implemented here but ScrollAlignment is
   // in Core which is a dependency violation.
   ASSERT_NOT_REACHED();