Make SharedWorker blob URL behavior aligned with the specification

Upon https://w3c.github.io/ServiceWorker/#control-and-use-worker-client, workers should inherit controllers for the blob URL. However, existing code allows only DedicatedWorkers to inherit the controller, and SharedWorkers do not inherit the controller. Setting the policy to Enabled or leaving it unset means Google Chrome inherit the controller if a blob URL is used as a SharedWorker URL. Setting the policy to Disabled leaves the behavior not aligned with the specification as-is. This policy is intended to be temporary and will be removed in the future.