[whatwg] Example wrong in web workers

[Simon Pieters]

Web Workers has the following in some example (twice):

// support being used as a shared worker as well as a dedicated worker
if (this.onmessage) // dedicated worker
   ....

This ought to be doing something like (typeof this.onmessage !=  
'undefined') , as the event property is presumably 'null' by the time of  
the test.

-- 
Simon Pieters
Opera Software