Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/platform/scroll/ScrollTypes.h

Index: third_party/WebKit/Source/platform/scroll/ScrollTypes.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollTypes.h b/third_party/WebKit/Source/platform/scroll/ScrollTypes.h
index 63a564a53903fd834a80933e7d51ab4ccdd51c4f..008835351d83fc8580ccc8ae13b1b36a65ac924f 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollTypes.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollTypes.h
@@ -76,14 +76,16 @@ enum ScrollType {
   kProgrammaticScroll,
   kClampingScroll,
   kCompositorScroll,
-  kAnchoringScroll
+  kAnchoringScroll,
+  kSequencedSmoothScroll
 };
 
 // An explicit scroll is one that was requested by the user or the webpage.
 // An implicit scroll is a side effect of a layout change.
 inline bool IsExplicitScrollType(ScrollType scroll_type) {
   return scroll_type == kUserScroll || scroll_type == kProgrammaticScroll ||
-         scroll_type == kCompositorScroll;
+         scroll_type == kCompositorScroll ||
+         scroll_type == kSequencedSmoothScroll;
 }
 
 // Convert logical scroll direction to physical. Physical scroll directions are
@@ -181,6 +183,8 @@ enum ScrollInertialPhase {
 
 enum ScrollbarOrientation { kHorizontalScrollbar, kVerticalScrollbar };
 
+enum ScrollOrientation { kHorizontalScroll, kVerticalScroll };
+
 enum ScrollbarMode { kScrollbarAuto, kScrollbarAlwaysOff, kScrollbarAlwaysOn };
 
 enum ScrollbarControlSize { kRegularScrollbar, kSmallScrollbar };