Remove duplicate function definition

getDOMDocument is already defined a few lines below, using the more
standard "self" reference rather than "this".
Merge pull request #831 from peitschie/odt-doc-codefix

Remove duplicate function definition
Cope with test names containing angle brackets
Verify the number of steps vs. expected number of cursor positions
Fix doc length check when iterating backwards
Report one test per cursor position document fragment
Print function result rather than function.toString for test description
Merge pull request #783 from peitschie/test-improvements

Clean up OdtDocument cursor position tests
Reduce the number of places aware that the root element can be replaced

Replacing the root element is currently a by-product of the undo impl.
Reducing the number of places aware of this impl detail helps ensure
future undo managers have less clean-up work to do when this behaviour
is finally removed.