Added Firefox 36.

Also, moved 'global symbol registry' into the Symbol category. This closes #324.
Merge pull request #346 from webbedspace/ff36

Added Firefox 36
Latest webkit now has String#includes
Added RegExp#flags and yield sending tests.
Merge pull request #343 from webbedspace/flags

Added RegExp#flags and yield-sending tests.
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'.
Merge pull request #348 from webbedspace/miscfix

Several misc. fixes.