12/04/15 00:39:49.83
naturalHeightとnaturalWidthで元の画像サイズが取れる
natural*がないブラウザはnew Image(url)でwidthとheightをとる
if(this.naturalHeight) {
this.height = this.naturalHeight;
this.width = this.naturalWidth;
} else {
var img = new Image(this.src);
this.height = img.height;
this.width = img.width;
}