CSSValue Immediates: Add move operators to CSSPrimitiveValue

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 8e8ec00fd043e8a2beaafbaab338c7392da5f8ae..2bf16b0b796dcc308f43083327a4cc1bdf9af0fd 100644
--- a/Source/core/css/CSSValue.h
+++ b/Source/core/css/CSSValue.h
@@ -80,7 +80,10 @@ public:
 
     ~CSSValue()
     {
-        deref();
+        // Although m_data can't be null, a move constructor from NullableCSSValue
+        // could make it null for a short time.
+        if (m_data)
+            deref();
     }
 
     CSSValue& operator=(const CSSValue& rhs)
@@ -91,6 +94,18 @@ public:
         return *this;
     }
 
+    CSSValue& operator=(CSSValue&& rhs)
+    {
+        m_data = rhs.m_data;
+        rhs.m_data.clear();
+        return *this;
+    }
+
+    CSSValue(CSSValue&& rhs)
+    {
+        m_data = rhs.m_data;
+    }
+
     bool operator==(const CSSValue& other) const
     {
         if (m_data == other.m_data)
@@ -269,6 +284,12 @@ public:
         return m_data;
     }
 
+    NullableCSSValue(NullableCSSValue&& rhs)
+    {
+        m_data = rhs.m_data;
+        rhs.m_data = nullptr;
+    }
+
     NullableCSSValue& operator=(const NullableCSSValue& rhs)
     {
         rhs.ref();
@@ -277,6 +298,13 @@ public:
         return *this;
     }
 
+    NullableCSSValue& operator=(NullableCSSValue&& rhs)
+    {
+        m_data = rhs.m_data;
+        rhs.m_data.clear();
+        return *this;
+    }
+
     bool operator==(const NullableCSSValue& rhs) const
     {
         if (m_data == rhs.m_data)