Add CSS support for Containment

third_party/WebKit/Source/core/style/ComputedStyleConstants.h

Index: third_party/WebKit/Source/core/style/ComputedStyleConstants.h
diff --git a/third_party/WebKit/Source/core/style/ComputedStyleConstants.h b/third_party/WebKit/Source/core/style/ComputedStyleConstants.h
index 14d68311b17f126c16d86b27e5163038205b948e..e15b5cb2cac97a89f361f2e4e315227d3805c179 100644
--- a/third_party/WebKit/Source/core/style/ComputedStyleConstants.h
+++ b/third_party/WebKit/Source/core/style/ComputedStyleConstants.h
@@ -485,6 +485,17 @@ inline TouchAction& operator&= (TouchAction& a, TouchAction b) { return a = a &
 
 enum EIsolation { IsolationAuto, IsolationIsolate };
 
+static const size_t ContainmentBits = 3;
+enum Containment {
+    ContainsNone = 0x0,
+    ContainsLayout = 0x1,
+    ContainsStyle = 0x2,
+    ContainsPaint = 0x4,
+    ContainsStrict = ContainsLayout | ContainsStyle | ContainsPaint,
+};
+inline Containment operator| (Containment a, Containment b) { return Containment(int(a) | int(b)); }
+inline Containment& operator|= (Containment& a, Containment b) { return a = a | b; }
+
 enum ItemPosition {
     ItemPositionAuto,
     ItemPositionStretch,