Emit scrambles variables if passing 4+ parameters with a callback, in IE9.

Odd title but this is a very specific issue, it seems. I've only seen this happen in Internet Explorer 9.

If you emit four or more variables with the last parameter being a function. When the function is passed through, "asyncAngularify", it also causes the third parameter (index 2) to change in to the resulting function.

E.g.

`angularSocket.emit("MyEvent", dataA, dataB, dataC, someCallback);`

Will get passed to socket as:

`emit("MyEvent", dataA, wrappedCallback, dataC, wrappedCallback);`

I believe this is a crazy issue to do with IE9s interpretation of the function. The function is defined as:

`emit: function (eventName, data, callback)`

Yet these parameters are never used, however, it does do:

`var callback = arguments[lastIndex];`

The key part here being that callback has been declared twice. Once, as parameter 3 of the arguments array (function definition) and now once as the final parameter of the arguments. So when:

`callback = asyncAngularify(socket, callback);`

happens, I believe it overwrites both `arguments[2]` and `arguments[length - 1]`

The fix for me so far is just to remove the variables in the function definition. Other methods would be to rename the parameters so there are no conflicting ones.