Bug 1030399 - remove semi-spammy warning from xptiInterfaceInfo.cpp; r=bholley

This warning isn't that helpful anymore, because it means that we don't
have interface info from an .xpt.  For DOM interfaces, that's OK,
because we'll have shimmed interface info instead.  So just remove the
warnings.

xpcom/reflect/xptinfo/xptiInterfaceInfo.cpp

@@ -362,7 +362,6 @@ xptiInterfaceEntry::GetEntryForParam(uint16_t methodIndex,
     // This can happen if a declared interface is not available at runtime.
     if(!theEntry)
     {
-        NS_WARNING("Declared InterfaceInfo not found");
         *entry = nullptr;
         return NS_ERROR_FAILURE;
     }