Remove VoidVal.

There are no undefined constants in IDL.
auto merge of #3942 : Ms2ger/servo/VoidVal, r=jdm

There are no undefined constants in IDL.
Remove tests/content/test_document_adoptNode.html.

It is already covered by:

  dom/nodes/Document-adoptNode.html
Remove tests/content/test_document_compatMode.html.

It is already covered by:

  html/dom/documents/resource-metadata-management/document-compatmode-03.html
  dom/nodes/Document-constructor.html
  dom/nodes/DOMImplementation-createHTMLDocument.html
auto merge of #3945 : Ms2ger/servo/rm-tests, r=Manishearth
Bug #3811 - Extracted the script task handlers into methods
auto merge of #3915 : shinglyu/servo/bug3811, r=jdm

This is a fix for bug #3811 , thank you.