roundpen-array-prototype-find

ES6 Array.prototype.find ponyfill

``javascript
var find = require('roundpen-array-prototype-find')

find.call([ 1, 3, 5, 7, 9 ], function(x) {
return x > 4
}) // => 5

find.call([ 1, 3, 5, 7, 9 ], function(x, index) {
return index === 3
}) // => 7

find.call([ 1, 3, 5, 7, 9 ], function(x, index, list) {
return index === list.length - 1
}) // => 9

find.call([ 1, 3, 5, 7, 9 ], function(x) {
return x > 100
}) // => undefined

function aPredicate(x) {
return true
}

find.call([ ], aPredicate) // => undefined

try {
find.call([ ], null)
} catch (e) {
e instanceof TypeError // => true
}

try {
find.call(null, aPredicate)
} catch (e) {
e instanceof TypeError // => true
}

try {
find.call(undefined, aPredicate)
} catch (e) {
e instanceof TypeError // => true
}
``