Avoid memory leak in RCTWebSocketModule

Summary: Though this module is dev-only, if not connected to the packager it will collect websockets forever. Some estimate it'll take up 200MB after like 20 minutes.

Reviewed By: shergin

Differential Revision: D6464304

fbshipit-source-id: bef1ce967e4c13dd29e3c7ab4228e9c88d02c157

Libraries/WebSocket/RCTWebSocketModule.m

@@ -163,6 +163,7 @@ - (void)webSocket:(RCTSRWebSocket *)webSocket didFailWithError:(NSError *)error
 {
   NSNumber *socketID = [webSocket reactTag];
   _contentHandlers[socketID] = nil;
+  _sockets[socketID] = nil;
   [self sendEventWithName:@"websocketFailed" body:@{
     @"message": error.localizedDescription,
     @"id": socketID
@@ -176,6 +177,7 @@ - (void)webSocket:(RCTSRWebSocket *)webSocket
 {
   NSNumber *socketID = [webSocket reactTag];
   _contentHandlers[socketID] = nil;
+  _sockets[socketID] = nil;
   [self sendEventWithName:@"websocketClosed" body:@{
     @"code": @(code),
     @"reason": RCTNullIfNil(reason),