Several misc. fixes.

 * Fixed the 'Object static methods accept primitives' misc. test (closes #347).
 * Added an 'accessors aren't constructors' misc. test.
 * Fixed the Traceur result for the 'no "prototype" property' arrow test.
 * Added a footnote explaining `__createIterableObject()`.
 * Fixed a Firefox footnote for Array.prototype.values.
 * Added two more Proxy tests involving the prototype chain, partially replacing the two Firefox notes about 'get' and 'set'.