StageText: Programmatic insertText and appendText calls do not behave like manually inserted text.

Steps to reproduce:
1. Run the attached apk.
2. Type "Fish" into the TextArea.
3. Hit the button for "stick".
4. Rerun the attached apk.
5. Hit the button for "Fish".
6. Hit the button for "stick".

Actual Results:
"stickFish" is displayed instead of "Fishstick".

Expected Results:
The insertion point for the text is updated to the end of the run of text when "insertText" is called, just like if it had been typed in manually. Both methods should result in "Fishstick".