Implement CSS: scroll-boundary-behavior

third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp b/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
index aa30b74edac99a047ff1c1d1eb0896ab0d20f2e5..0475a920f32cdc6e6d045d548ef7621f76898497 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserFastPaths.cpp
@@ -845,6 +845,12 @@ bool CSSParserFastPaths::IsValidKeywordPropertyAndValue(
       DCHECK(RuntimeEnabledFeatures::cssScrollSnapPointsEnabled());
       return value_id == CSSValueNone || value_id == CSSValueMandatory ||
              value_id == CSSValueProximity;
+    case CSSPropertyScrollBoundaryBehaviorX:
+      return value_id == CSSValueAuto || value_id == CSSValueContain ||
+             value_id == CSSValueNone;
+    case CSSPropertyScrollBoundaryBehaviorY:
+      return value_id == CSSValueAuto || value_id == CSSValueContain ||
+             value_id == CSSValueNone;
     default:
       NOTREACHED();
       return false;
@@ -958,6 +964,8 @@ bool CSSParserFastPaths::IsKeywordPropertyID(CSSPropertyID property_id) {
     case CSSPropertyWordWrap:
     case CSSPropertyWritingMode:
     case CSSPropertyScrollSnapType:
+    case CSSPropertyScrollBoundaryBehaviorX:

[bokan, 2017/05/19 19:35:57]

Nit: place these below CSSPropertyScrollBehavior, these are "almost"
alphabetically sorted. 

[sunyunjia, 2017/05/25 20:07:10]

Done.

+    case CSSPropertyScrollBoundaryBehaviorY:
       return true;
     case CSSPropertyJustifyContent:
     case CSSPropertyAlignContent: