Bug 1182996 - Fix and add missing namespace comments. rs=ehsan

The bulk of this commit was generated by running:

  run-clang-tidy.py \
    -checks='-*,llvm-namespace-comment' \
    -header-filter=^/.../mozilla-central/.* \
    -fix

netwerk/protocol/websocket/WebSocketChannel.cpp

@@ -2189,7 +2189,7 @@ public:
   }
 };
 
-} // anonymous namespace
+} // namespace
 
 void
 WebSocketChannel::CleanupConnection()
@@ -3745,7 +3745,7 @@ WebSocketChannel::SaveNetworkStats(bool enforce)
 #endif
 }
 
-} // namespace mozilla::net
+} // namespace net
 } // namespace mozilla
 
 #undef CLOSE_GOING_AWAY