Major cleanup of JS sample code.

Update of PR #17.

Move to a more modern JS style for the Tracer JS example. Includes:

 * Strict mode conformance
 * Use methods instead of prototype de-ref indirections
 * Better use of `Object.create()` in subclasses
 * Better defaults in the web example page
 * Updates previous PR to remove `ToNumber()`'s in math methods.