Faster removeChildren

Use `textContent = ""` instead of `innerHTML = ""` in `!IE` browsers. 
This will avoid html parser creation (at least in webkit).
FYI: 
Testing results: http://jsperf.com/removechildren/8
Browser compatability: http://www.quirksmode.org/dom/w3c_html.html
Spec: https://developer.mozilla.org/ru/docs/DOM/Node.textContent