Both SWF-defined and dynamic TextFields rely on an object constructed by the _global.TextField constructor. If this doesn't exist or is not a function, no valid as_object will be constructed, yet all Gnash TextField objects must have an associated as_object.

The crashes and memory corruptions should now be fixed, but although there should already be tests for what happens when _global.TextField is replaced (not sure where), there are evidently none for what happens when it is not a function.

This should be tested both to avoid regressions and to see what the effect is; the bug report is a reminder.