- Make switch-statement report correct error position when it fails to evaluate the condition.
- Make for-statement report correct error position when it fails to evaluate the initializer.
- For the condition of `if/for/while/do-while/do-until` statements, the sequence point update is either duplicate in some cases (for `if/for/while`) which causes debugger to stop at the condition twice before moving forward, or missing (for `do-while/do-until`) which causes debugger to skip the condition. They are fixed.
The fix causes a problem in debugging. When stepping over the scripts in debugging mode, the debugger will stop at the switch statement condition expression twice at the very beginning -- one for evaluating the condition, and one for iterating the condition.
