Fixes 4331, 4332 - WebSocket.length and instanceof WebSocket

Fixes 4331, 4332 - WebSocket.length and instanceof WebSocket

[kzar, 2016-08-15 19:29:00]

Patch Set 1

Tested on chrome 40, 52 and Safari 9. Made sure it actually works on several
websites + blocks. Also evaluated things like this:

WebSocket.length;
new WebSocket("ws://echo.websocket.org") instanceof WebSocket;
WebSocket.toString();
WebSocket.hasOwnProperty("prototype");

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js
File include.preload.js (right):

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js#...
include.preload.js:401: function WrappedWebSocket(url)
For some reason if I did this in one step I no longer had the WrappedWebSocket
reference outside of the function! Don't ask me why...

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js#...
include.preload.js:422: {value: RealWebSocket.prototype});
We have to define the prototype here so that `... instanceof WebSocket` works.

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js#...
include.preload.js:429: prototype: {value: RealWebSocket.prototype}
We have to define the prototype here so that
`WebSocket.hasOwnProperty("prototype")` is true.

[Wladimir Palant, 2016-08-15 20:20:35]

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js
File include.preload.js (right):

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js#...
include.preload.js:422: {value: RealWebSocket.prototype});
On 2016/08/15 19:29:00, kzar wrote:
> We have to define the prototype here so that `... instanceof WebSocket` works.

Since the website cannot access WrappedWebSocket, just setting
WrappedWebSocket.prototype will do - no need to define a non-configurable
property.

[kzar, 2016-08-15 20:36:21]

Patch Set 2 : Assign WrappedWebSocket.prototype more simply

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js
File include.preload.js (right):

https://codereview.adblockplus.org/29349816/diff/29349817/include.preload.js#...
include.preload.js:422: {value: RealWebSocket.prototype});
On 2016/08/15 20:20:35, Wladimir Palant wrote:
> On 2016/08/15 19:29:00, kzar wrote:
> > We have to define the prototype here so that `... instanceof WebSocket`
works.
> 
> Since the website cannot access WrappedWebSocket, just setting
> WrappedWebSocket.prototype will do - no need to define a non-configurable
> property.

Done.

[Sebastian Noack, 2016-08-15 21:13:25]

LGTM

[Wladimir Palant, 2016-08-15 21:22:56]

LGTM