* The method can be chained just as the other methods on NS_MutateURI.
* In case the mutator object does not implement the interface, mStatus will be set to an error code.
* This is useful when you are constructing a new URI and the type of the mutator is known. I expect a future patch will add a MaybeApply method, that does not set mStatus to an error code if the mutator does not implement the interface.
* This patch changes nsHostObjectProtocolHandler::NewURI to use the new method and avoid a static_cast<nsHostObjectURI*>(uri)
MozReview-Commit-ID: 9kvXJX54gUP
This also changes URIUtils.cpp:DeserializeURI() to use the mutator to instantiate new URIs, instead of using their default constructor.
MozReview-Commit-ID: JQOvIquuQAP
