Move addEventListener.optional.useCapture.html to dom/ and clean it up.
Move dispatchEvent.return.value.html to dom/ and clean it up.
This fixes test description
Basic single-byte decoder tests
typo
use separate video elements for each subtest

so that other subtests are not affected when each modifies the video element.
use step_func and step_func_done to simplify some tests
expect sourceended after MediaSource.endOfStream() instead of sourceclose

http://www.w3.org/TR/media-source/#mediasource-events
http://www.w3.org/TR/media-source/#idl-def-ReadyState
wrap assert_throws() call in appropriate subtest step
Update to latest wptserve
Cleanup of Microsoft's worker tests
Make Worker_ErrorEvent* tests work
Fix WorkerLocation_port test. Fixes #1397
Share some more code in the DOMImplementation#createHTMLDocument test.
Share code between DOMImplementation#createHTMLDocument tests in DOM and HTML.
Introduce variables to clarify DOMImplementation-createHTMLDocument.html.
Add some more checks to DOMImplementation-createHTMLDocument.html.

These checks are inspired by the relevant Servo test.
Address some nits from @zcorpan
Merge pull request #1311 from Ms2ger/createHTMLDocument

Cleanup and improve DOMImplementation#createHTMLDocument tests; r=zcorpan
Update to latest wptserve