If QueryHandlerInterface returns E_NOINTERFACE, the proxy will be queried for the interface.
However, the handler might know that the interface is definitely not available and could thus avoid a pointless cross-process call.
To facilitate this, the handler can now return S_FALSE to signal that the proxy should not be queried, thus immediately returning E_NOINTERFACE to the client.
MozReview-Commit-ID: 4RtBsA9BTOV
