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 436e96d1ad26d529cc8f56b14b1223e49e04e785..60c8b09e9237768fedd7e6f26dad5c01bfc7a298 100644
--- a/third_party/WebKit/Source/core/layout/LayoutObject.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutObject.cpp
@@ -637,13 +637,15 @@ 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;
 }