Partial implementation of CSSVariablesMap for CSS Variables CSSOM

Source/core/css/CSSValue.cpp

Index: Source/core/css/CSSValue.cpp
diff --git a/Source/core/css/CSSValue.cpp b/Source/core/css/CSSValue.cpp
index c9435ab2148da09f44139c7460076514d1135c5a..bce26452e7277cc92f35e50e480bc8deef6cc439 100644
--- a/Source/core/css/CSSValue.cpp
+++ b/Source/core/css/CSSValue.cpp
@@ -300,7 +300,7 @@ String CSSValue::cssText() const
     case CSSShaderClass:
         return static_cast<const CSSShaderValue*>(this)->customCssText();
     case VariableClass:
-        return static_cast<const CSSVariableValue*>(this)->value();
+        return toCSSVariableValue(this)->value();
     case SVGColorClass:
         return static_cast<const SVGColor*>(this)->customCssText();
     case SVGPaintClass:
@@ -429,7 +429,7 @@ void CSSValue::destroy()
         delete static_cast<CSSShaderValue*>(this);
         return;
     case VariableClass:
-        delete static_cast<CSSVariableValue*>(this);
+        delete toCSSVariableValue(this);
         return;
     case SVGColorClass:
         delete static_cast<SVGColor*>(this);