bug 1153288 - Update mock to 1.3.0
bug 1153288 - Update mock to 1.3.0

mdn/browsercompat,mdn/browsercompat,renoirb/browsercompat,jwhitlock/web-platform-compat,mdn/browsercompat,renoirb/browsercompat,jwhitlock/web-platform-compat,jwhitlock/web-platform-compat,renoirb/browsercompat