Use JS class syntax in harness code

[smfr]

Convert the harness code (and a bit of test code) to use JS class syntax, replacing Utilities.createClass() and Utilities.createSubclass with class and extend, fixing the formatting as appropriate.

Mostly mechanical, other than passing window.location to Utilities.parseParameters so it doesn't depend on the current window object, and fixing a this access in calculateScore().

Some of these classes, like Point, are used in test code, so this may have some impact on test score.

[smfr]

Marked "non-trivial" since the changes touch test code.