[TLF 2482538] Setting boolean TextLayoutFormat properties to "false" makes them true

Steps to reproduce:
1. Run code like:
var format:TextLayoutFormat = new TextLayoutFormat();
format.lineThrough = "false";
2. Inspect format in a debugger or apply that format to some rich text.

Actual Results:
format.lineThrough is true.
The text is rendered with a strikethrough.

Expected Results:
format.lineThrough is false.
The text is rendered without a strikethrough.

Workaround (if any):
Convert strings to booleans before setting TextLayoutFormat attributes.