Implement CSS: scroll-boundary-behavior

third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp

Index: third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
diff --git a/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp b/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
index 1192364103285936c159c24209515a8382b4ff2e..15e7c9cef78e76a12c8e994b486b8e62c5830658 100644
--- a/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
+++ b/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
@@ -3661,6 +3661,14 @@ const CSSValue* ComputedStyleCSSValueMapping::Get(
     case CSSPropertyScrollSnapDestination:
       return ValueForScrollSnapDestination(style.ScrollSnapDestination(),
                                            style);
+    case CSSPropertyScrollBoundaryBehavior:
+      if (style.ScrollBoundaryBehaviorX() == style.ScrollBoundaryBehaviorY())
+        return CSSIdentifierValue::Create(style.ScrollBoundaryBehaviorX());
+      return nullptr;
+    case CSSPropertyScrollBoundaryBehaviorX:
+      return CSSIdentifierValue::Create(style.ScrollBoundaryBehaviorX());
+    case CSSPropertyScrollBoundaryBehaviorY:
+      return CSSIdentifierValue::Create(style.ScrollBoundaryBehaviorY());
     case CSSPropertyTranslate: {
       if (!style.Translate())
         return CSSIdentifierValue::Create(CSSValueNone);