Q:

Why Firexfox and IE cannot open a link (anchor) inside a  tag.

Why IE and Firefox cannot open a link inside the button tag, In chrome
it opens the link in same window.
Example:
<button type="button"><a href="http://stackoverflow.com">stackoverflow</a></button>

A:

It'not allowed to have link inside a button, according to HTML5 specifications
HTML5 reference from W3

Content model: Phrasing content, but there must be no interactive
  content descendant.

a is interactive content descendant
Interactive content description

