Changes in original fontSize calculating

1) Temporary elements did not remove correctly
2) Code was changed to match JavaScript Style Guide (https://github.com/natgeo/javascript)
3) Optimization for js minimization

Notice: today I found that Respond.js plugin has similar font-size detection. But I found that all browsers calculate rem according to html element font-size. That mean that in case when font-size was changed by css or style attribute calculated font-size should take into consideration this value. Respond.js also resets this value like a body font-size. But this behavior doesn't match to browsers behavior (at least IE and FF works in this way)