Add tests for RegExp.prototype.compile (#632)

...uilt-ins/RegExp/prototype/compile/flags-string-invalid.js

...built-ins/RegExp/prototype/compile/flags-to-string-err.js

...exB/built-ins/RegExp/prototype/compile/flags-to-string.js

...exB/built-ins/RegExp/prototype/compile/flags-undefined.js

...t-ins/RegExp/prototype/compile/pattern-regexp-distinct.js

.../RegExp/prototype/compile/pattern-regexp-flags-defined.js

...p/prototype/compile/pattern-regexp-immutable-lastindex.js

...uilt-ins/RegExp/prototype/compile/pattern-regexp-props.js

...built-ins/RegExp/prototype/compile/pattern-regexp-same.js

...-ins/RegExp/prototype/compile/pattern-string-invalid-u.js

...lt-ins/RegExp/prototype/compile/pattern-string-invalid.js

...xB/built-ins/RegExp/prototype/compile/pattern-string-u.js

...nexB/built-ins/RegExp/prototype/compile/pattern-string.js

...ilt-ins/RegExp/prototype/compile/pattern-to-string-err.js

...B/built-ins/RegExp/prototype/compile/pattern-undefined.js

...exB/built-ins/RegExp/prototype/compile/this-not-object.js

...built-ins/RegExp/prototype/compile/this-obj-not-regexp.js