Remove unneeded compatibility polyfills

- `Object.create` supported with IE9+: https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Object/create#Browser_compatibility
- `Object.keys` supported with IE9+: https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Object/keys#Browser_compatibility
- `Array.prototype.filter` supported in IE9+: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter#Browser_compatibility
- `Array.prototype.indexOf` supported in IE9+: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf#Browser_compatibility
- `Array.prototype.map` supported in IE9+: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map#Browser_compatibility
- `Function.prototype.bind` supported in IE9+: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind#Browser_compatibility
- `String.prototype.trim` supported with IE9+: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim#Browser_compatibility
- `outerHTML` supported with Firefox 11+: https://developer.mozilla.org/en-US/docs/Web/API/Element/outerHTML#Browser_compatibility
- `window.devicePixelRatio` supported in IE11+: http://caniuse.com/#feat=devicepixelratio



Signed-off-by: Morris Jobke <hey@morrisjobke.de>