Show custom properties in the computed style pane of the inspector.

third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp

Index: third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
diff --git a/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp b/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
index 4f41f9a1f3e5d2d0e5374cee545bd78942b6560b..ef53f27a56d352cc1dcfff3777105ba4edc59bd8 100644
--- a/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
+++ b/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
@@ -1357,13 +1357,25 @@ static PassRefPtrWillBeRawPtr<CSSValue> valueForScrollSnapCoordinate(const Vecto
 
 PassRefPtrWillBeRawPtr<CSSValue> ComputedStyleCSSValueMapping::get(const AtomicString customPropertyName, const ComputedStyle& style)
 {
-    CSSVariableData* data = style.variables()->getVariable(customPropertyName);
+    StyleVariableData* variables = style.variables();
+    if (!variables)
+        return nullptr;
+
+    CSSVariableData* data = variables->getVariable(customPropertyName);
     if (!data)
         return nullptr;
 
     return CSSCustomPropertyDeclaration::create(customPropertyName, data);
 }
 
+const HashMap<AtomicString, RefPtr<CSSVariableData>>* ComputedStyleCSSValueMapping::getVariables(const ComputedStyle& style)
+{
+    StyleVariableData* variables = style.variables();
+    if (variables)
+        return variables->getVariables();
+    return nullptr;
+}
+
 PassRefPtrWillBeRawPtr<CSSValue> ComputedStyleCSSValueMapping::get(CSSPropertyID propertyID, const ComputedStyle& style, const LayoutObject* layoutObject, Node* styledNode, bool allowVisitedStyle)
 {
     const SVGComputedStyle& svgStyle = style.svgStyle();