Remove Object.keys ponyfill, since this library was never intended to support IE8

Author: developit

src/index.js

@@ -1,4 +1,4 @@
-import { objectKeys, encodeEntities, indent, isLargeString, styleObjToCss, assign, getNodeProps } from './util';
+import { encodeEntities, indent, isLargeString, styleObjToCss, assign, getNodeProps } from './util';
 
 const SHALLOW = { shallow: true };
 
@@ -88,7 +88,7 @@ function renderToString(vnode, context, opts, inner, isSvgMode) {
 	let s = '', html;
 
 	if (attributes) {
-		let attrs = objectKeys(attributes);
+		let attrs = Object.keys(attributes);
 
 		// allow sorting lexicographically for more determinism (useful for tests, such as via preact-jsx-chai)
 		if (opts && opts.sortAttributes===true) attrs.sort();

src/util.js

@@ -1,12 +1,6 @@
 // DOM properties that should NOT have "px" added when numeric
 export const IS_NON_DIMENSIONAL = /acit|ex(?:s|g|n|p|$)|rph|ows|mnc|ntw|ine[ch]|zoo|^ord/i;
 
-export const objectKeys = Object.keys || (obj => {
-	let keys = [];
-	for (let i in obj) if (obj.hasOwnProperty(i)) keys.push(i);
-	return keys;
-});
-
 export let encodeEntities = s => String(s)
 	.replace(/&/g, '&')
 	.replace(/</g, '&lt;')