brunoais/jquery — comment on commit 2c6dee1a258591efbd82284f08e7490a1a62504c
File: src/core.js line 442
By brunoais:

This can be read a browser detection. It is detection but it's just to prevent the bug in IE to cause mischief.
If this takes false positive, no harm is done. If it takes real positive then the problem is prevented if this takes negative, it's from a browser that follows HTML5 spec (E.g. firefox) or does not do any harm (E.g. Opera)