CSSValue Immediates: Make CSSPrimitiveValue a container

Source/core/css/CSSValue.h

Index: Source/core/css/CSSValue.h
diff --git a/Source/core/css/CSSValue.h b/Source/core/css/CSSValue.h
index 609dcbc85afcae15a768dc5b5debdca568aa6112..ac7df50a004ea2b8914057e1cfcd39f5a06dba76 100644
--- a/Source/core/css/CSSValue.h
+++ b/Source/core/css/CSSValue.h
@@ -22,6 +22,7 @@
 #define CSSValue_h
 
 #include "core/CoreExport.h"
+#include "core/css/CSSPrimitiveValue.h"
 #include "core/css/CSSValueObject.h"
 #include "platform/heap/Handle.h"
 #include "wtf/RefCounted.h"
@@ -67,6 +68,13 @@ public:
         ref();
     }
 
+    // Implicit conversion from CSSPrimitiveValue.
+    CSSValue(CSSPrimitiveValue cssPrimitiveValue)
+        : m_data(static_cast<CSSValueObject*>(cssPrimitiveValue.get()))
+    {
+        ref();
+    }
+
     ~CSSValue()
     {
         deref();
@@ -221,12 +229,19 @@ public:
         ref();
     }
 
+    // Implicit conversion from CSSPrimitiveValue.
+    NullableCSSValue(CSSPrimitiveValue cssPrimitiveValue)
+        : m_data(static_cast<CSSValueObject*>(cssPrimitiveValue.get()))
+    {
+        ref();
+    }
+
     ~NullableCSSValue()
     {
         deref();
     };
 
-    operator bool() const
+    explicit operator bool() const
     {
         return m_data;
     }
@@ -239,12 +254,12 @@ public:
         return *this;
     }
 
-    bool operator==(const NullableCSSValue& rhs)
+    bool operator==(const NullableCSSValue& rhs) const
     {
         return m_data ? rhs.m_data && m_data->equals(*rhs.m_data) : !bool(rhs.m_data);
     }
 
-    bool operator!=(const NullableCSSValue& rhs)
+    bool operator!=(const NullableCSSValue& rhs) const
     {
         return !(*this == rhs);
     }
@@ -348,6 +363,13 @@ inline bool compareCSSValueVector(const WillBeHeapVector<CSSValue, inlineCapacit
         return static_cast<thisType*>(value.get()); \
     }
 
+// Returns by value on purpose.
+inline CSSPrimitiveValue toCSSPrimitiveValue(const CSSValue& value)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(value.isPrimitiveValue());
+    return CSSPrimitiveValue(static_cast<CSSPrimitiveValue::CSSLargePrimitiveValue*>(value.get()));
+}
+
 } // namespace blink
 
 WTF_ALLOW_CLEAR_UNUSED_SLOTS_WITH_MEM_FUNCTIONS(blink::CSSValue);