Merge pull request #319 from pvginkel/missing-features

...totype/find/Array.prototype.find_empty-array-undefined.js

...ay/prototype/find/Array.prototype.find_length-property.js

...prototype/find/Array.prototype.find_modify-after-start.js

...type/find/Array.prototype.find_non-returning-predicate.js

...totype/find/Array.prototype.find_noncallable-predicate.js

...rototype/find/Array.prototype.find_predicate-arguments.js

...y/prototype/find/Array.prototype.find_push-after-start.js

...prototype/find/Array.prototype.find_remove-after-start.js

...prototype/find/Array.prototype.find_return-found-value.js

...Array/prototype/find/Array.prototype.find_this-defined.js

.../Array/prototype/find/Array.prototype.find_this-global.js

...ray/prototype/find/Array.prototype.find_this-is-object.js

...ray/prototype/find/Array.prototype.find_this-undefined.js