typeof WebSocket and XMLHttpRequest is "function" in IE, Firefox and Chrome, WebKit returns "object" here.
Already fixed in Bug 154038. Note however that this has nothing to do with being constructible or not. `typeof Node` returns "function" in all browsers as well but is not constructible. *** This bug has been marked as a duplicate of bug 154038 ***
You can confirm this by trying a nightly build: https://nightly.webkit.org