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 39124fac467439e890257eafb3ba8f60a9498469..dffcb8475168d921536fed629680c28d240fbbfd 100644
--- a/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
+++ b/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
@@ -3660,6 +3660,14 @@ 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);