The formatting of the IDL at 4.2.2 (http://www.w3.org/TR/workers/#dedicatedworkerglobalscope) is broken. See screenshot: http://gyazo.com/c8cea78268118dbfd30885b8fe009de8.png
The same formatting issue exists at 4.8.2 of http://dev.w3.org/html5/workers/ and http://www.w3.org/TR/workers/
I fixed it at http://www.w3.org/TR/workers/#dedicatedworkerglobalscope -- which is a static copy of the state of the spec on 2011-09-01, so as an implementor you really shouldn't be using that version, because it's already out of date :)
The formatting at http://dev.w3.org/html5/workers/#dedicatedworkerglobalscope is still broken but I don't know why. That version is auto-generated from Hixie's upstream source, and the formatting there is fine http://www.whatwg.org/specs/web-apps/current-work/multipage/workers.html#dedicatedworkerglobalscope
So, it seems there's a problem in the script that Hixie uses to generate the W3C version.