tests for chapter 8 'Instantiating Custom Elements'
improving tests according to Dominic's notes
improving tests according to Dominic's notes
improving and refactoring tests according to Dominic's notes
improving tests according to Dominic's notes
improving tests according to Dominic's notes
Merge pull request #895 from sgrekhov/submission/unipro-custom-elements-9

tests for chapter 8 'Instantiating Custom Elements'