Implement Element.scrollIntoView for scroll-behavior: smooth.

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

Index: third_party/WebKit/Source/core/layout/ScrollAlignment.cpp
diff --git a/third_party/WebKit/Source/core/layout/ScrollAlignment.cpp b/third_party/WebKit/Source/core/layout/ScrollAlignment.cpp
index 1f162fb1f3e2c68d94db4a215a19cd7e25b52f89..14b8f8114c12d9d1cba484488186653fd679554c 100644
--- a/third_party/WebKit/Source/core/layout/ScrollAlignment.cpp
+++ b/third_party/WebKit/Source/core/layout/ScrollAlignment.cpp
@@ -58,6 +58,10 @@ 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