function callback(userCallback, error, inlinePayload, attributesStylePayload)
        {
            if (error || !inlinePayload)
                userCallback(null, null);
            else
                userCallback(WebInspector.CSSStyleDeclaration.parsePayload(this, inlinePayload), attributesStylePayload ? WebInspector.CSSStyleDeclaration.parsePayload(this, attributesStylePayload) : null);
        }
@param {function(?WebInspector.CSSStyleDeclaration, ?WebInspector.CSSStyleDeclaration)} userCallback
@param {?Protocol.Error} error
@param {?CSSAgent.CSSStyle=} inlinePayload
@param {?CSSAgent.CSSStyle=} attributesStylePayload
@this {WebInspector.CSSStyleModel}