Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/core/layout/ScrollAlignment.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 40 matching lines @@
     ScrollAlignmentNoScroll, ScrollAlignmentCenter, ScrollAlignmentClosestEdge};
 const ScrollAlignment ScrollAlignment::alignToEdgeIfNeeded = {
     ScrollAlignmentNoScroll, ScrollAlignmentClosestEdge,
     ScrollAlignmentClosestEdge};
 const ScrollAlignment ScrollAlignment::alignCenterAlways = {
     ScrollAlignmentCenter, ScrollAlignmentCenter, ScrollAlignmentCenter};
 const ScrollAlignment ScrollAlignment::alignTopAlways = {
     ScrollAlignmentTop, ScrollAlignmentTop, ScrollAlignmentTop};
 const ScrollAlignment ScrollAlignment::alignBottomAlways = {
     ScrollAlignmentBottom, ScrollAlignmentBottom, ScrollAlignmentBottom};
+const ScrollAlignment ScrollAlignment::alignLeftAlways = {
+    ScrollAlignmentLeft, ScrollAlignmentLeft, ScrollAlignmentLeft};
+const ScrollAlignment ScrollAlignment::alignRightAlways = {
+    ScrollAlignmentRight, ScrollAlignmentRight, ScrollAlignmentRight};
 
 #define MIN_INTERSECT_FOR_REVEAL 32
 
 LayoutRect ScrollAlignment::getRectToExpose(const LayoutRect& visibleRect,
                                             const LayoutRect& exposeRect,
                                             const ScrollAlignment& alignX,
                                             const ScrollAlignment& alignY) {
   // Prevent degenerate cases by giving the visible rect a minimum non-0 size.
   LayoutRect nonZeroVisibleRect(visibleRect);
   LayoutUnit minimumLayoutUnit;
@@ skipping 95 matching lines @@
   else if (scrollY == ScrollAlignmentCenter)
     y = exposeRect.y() +
         (exposeRect.height() - nonZeroVisibleRect.height()) / 2;
   else
     y = exposeRect.y();
 
   return LayoutRect(LayoutPoint(x, y), nonZeroVisibleRect.size());
 }
 
 }  // namespace blink