Fix 3 AlbTextEditor*Test

[tinchodias]

As of today, in master, these tests fail/error:

[tinchodias]

Many are like:

 ✗ #test_overwrite_Hello_World_with_S_in_Hello_World (0ms)
Instance of AlbEditorElement did not understand #editor:
AlbEditorElement(Object)>>doesNotUnderstand: #editor:
AlbTextEditorLineSegmentTest>>test_emptyEditor ...editor: aTextEditor
AlbTextEditorLineSegmentTest>>test_insert_Hello_World_inEmptyAt_0 ...test_emptyEditor
AlbTextEditorLineSegmentTest>>test_overwrite_Hello_World_with_S_in_Hello_World ...test_insert_Hello_World_inEmptyAt_0
AlbTextEditorLineSegmentTest(TestCase)>>performTest

other are like:

 ✗ #test_cursor_moveToLineStart_in_cursors_at_0 (0ms)
Instance of AlbTextEditorNavigatorTest did not understand #test_cursor_add_at_0_in_multi_lines
AlbTextEditorNavigatorTest(Object)>>doesNotUnderstand: #test_cursor_add_at_0_in_multi_lines
AlbTextEditorNavigatorTest>>test_cursor_moveToLineStart_in_cursors_at_0 ...test_cursor_add_at_0_in_multi_lines
AlbTextEditorNavigatorTest(TestCase)>>performTest

@plantec do you remember what happened with that editor:?

[tinchodias]

@plantec I'm working on the code styler for Pharo 13 (pharo-graphics/Bloc#745) and I realized that I don't know how to actually open an example to see it in action, because examples send editor: to the element and that's DNU. Example: ToSandBox class>>#example_CodeEditor

Do you know what's this DNU? or I track it in the history?