Under certain conditions, the renderContent method will deterministically throw multiple IndexOutOfBoundsExceptions, which are silently discarded in a catch block. This impacts performance somewhat in these situations.

Reproduction steps:
- Run the latest monkey tester
- Set breakpoint to com.sun.javafx.sg.prism.NGGroup:262, the only catch block in the method
- Navigate to Tools -> System Info in monkey tester
- In the System Info text field, select some text with the mouse
- Multiple exceptions should be thrown

Caused by
startPos = -1