IE8 support

I needed this library to work with IE8. (because it's a dependency of yields/select) The changes here are not as drastic as I expected, so I hope it will be considered for inclusion.

 * using `component/each` instead of `Array#forEach`
 * using `juliangruber/isarray` instead of `Array.isArray`
 * using `innerText || textContent` fallback for text
 * using `matthewp/text` for tests (could not use in lib because document-fragments don't work like normal nodes in IE8)
 * adjusted some unit tests to account for "differences" with IE8 (capitalizing tag names, etc)