Update RegExp tests (#614)

The RegExpBuiltinExec internal operation was modified in March of 2016
[1]: instead of referencing the `global` and `sticky` properties of the
"this" value, the algorithm now infers those values from the object's
[[OriginalFlags]] internal slot.

This change invalidated a number of tests. In cases where the change
resulted in an observable behavior, update the tests to assert the
latest specification text. In cases where the change removed a
previously-observable behavior, remove the files completely.

Specification text change set:

>        1. Assert: Type(_S_) is String.
>        1. Let _length_ be the number of code units in _S_.
>        1. Let _lastIndex_ be ? ToLength(? Get(_R_, `"lastIndex"`)).
>      - 1. Let _global_ be ToBoolean(? Get(_R_, `"global"`)).
>      - 1. Let _sticky_ be ToBoolean(? Get(_R_, `"sticky"`)).
>      + 1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
>      + 1. If _flags_ contains `"g"`, let _global_ be *true*, else let _global_ be *false*.
>      + 1. If _flags_ contains `"y"`, let _sticky_ be *true*, else let _sticky_ be *false*.
>        1. If _global_ is *false* and _sticky_ is *false*, let _lastIndex_ be 0.
>        1. Let _matcher_ be the value of _R_'s [[RegExpMatcher]] internal slot.
>      - 1. Let _flags_ be the value of _R_'s [[OriginalFlags]] internal slot.
>        1. If _flags_ contains `"u"`, let _fullUnicode_ be *true*, else let _fullUnicode_ be *false*.
>        1. Let _matchSucceeded_ be *false*.
>        1. Repeat, while _matchSucceeded_ is *false*

[1] https://github.com/tc39/ecma262/pull/494