md-fab icon position is not right with href attribute

[allenhwkim]

As you see here, http://plnkr.co/edit/YnTpzONccsaQk7KDNRIL?p=preview

When md-fab button has a href, the icon position gets wrong top positioned.

The easy fix for this is, to set line-height of "a" in md-fab. demo

 a.md-fab {
    line-height: 4.9rem; /* 49px; 56(height)-12(padding)+5(margin) */
  } 

However, IMHO, the ideal fix for this is to position items in md-fab with flex box, 'center center', so that this is not necessary.