This is the source code of a script to be executed.
If VM mode is set, print the disassembly of bytecode before running if true.
If the script has a return statement with an expression, this value will be the result of that expression otherwise it will be ScriptAny.UNDEFINED
This is the main entry point for evaluating a script program. If the useVM option was set in the constructor, bytecode compilation and execution will be used, otherwise tree walking.