third bunch of custom elements tests
improving tests according to Dominic's notes
improving tests according to Dominic's notes
fixing line endings
improving tests according to Dominic's notes
fixing bug in test share-registry-import-document.html
improving tests according to Dominic's notes
refactoring: extracting common method
XML document tests removed and code formatting
Merge pull request #578 from sgrekhov/submission/unipro-custom-elements-3

Merge Custom Element registry sharing tests.