Don't pass protocols to WebSocket and return false

Passing an empty string, an empty array, an empty object, or undefined to WebSocket in iOS 5 produces the following errors:
```
JavaScript: Error
http://192.168.1.100
Wrong protocol for WebSocket ''

JavaScript: Error
undefined
SYNTAX_ERR: DOM Exception 12: An invalid or illegal string was specified.
```

Also the function now returns **false** instead of an object so it's easier to check if the client doesn't support WebSockets and fallback to long polling or something else.