Test Worker constructor functionality. Should print a series of PASS messages, followed with DONE.

PASS: toString exception propagated correctly.
PASS: trying to create workers recursively resulted in an exception (RangeError: Maximum call stack size exceeded.)
PASS: invoking Worker constructor without arguments resulted in an exception (SyntaxError: Not enough arguments)
PASS: onerror invoked for a script that could not be loaded.
DONE

