IE backslash hack on .img-responsive stretches images in IE<11

Created by: isherwood

A width statement on .img-responsive stretches images beyond their pixel dimensions in IE <= 10. It wasn't there before v3.2.0, and I can't seem to find any explanation or discussion of the issue.

.img-responsive, .thumbnail > img, .thumbnail a > img, .carousel-inner > .item > img, .carousel-inner > .item > a > img { width: 100% \9; }