UITextField.truncateToFit(): dead code and performance

The problem originates around line 1842 of UITextField (v3.2). It looks like someone tried to fix this performance issue before; This line uses the relative size of available space and actual space to estimate where to truncate. Unfortunately as SDK-14981 pointed out slice returns a copy and there is no assignment, so this becomes dead code.

The result of the bug is that for long strings a linear trial-and-error - with string copies for each slice - takes a long time. If there are many UITextFields with lengthy text, this operation becomes a joke.

I found this in v3.2 and it was unchanged at least up to v4.0. I am submitting a contrib agreement and will create a patch myself if approved.

Steps to reproduce:
1. Create a panel with many UITextFields that have long source-text Strings.
2.
3.

Actual Results:

Rendering takes a long time.

Expected Results: -

Workaround (if any): -