Create a new instance of CORSPolicy.
Values are set to match defaultPolicy.
Source
CORSPolicy() {
var def = defaultPolicy;
allowedOrigins = new List.from(def.allowedOrigins);
allowCredentials = def.allowCredentials;
exposedResponseHeaders = new List.from(def.exposedResponseHeaders);
allowedMethods = new List.from(def.allowedMethods);
allowedRequestHeaders = new List.from(def.allowedRequestHeaders);
cacheInSeconds = def.cacheInSeconds;
}