I'd imagine a somewhat wide applause echoed from the front-end community when Microsoft announced in Jan 2015 that they were working on a ground-up new browser codenamed Spartan.

Over years Internet Explorer has developed a stigma amongst front-end developers. Microsoft made some attempts in IE10 and IE11 to align itself with already adopted W3C standards but decades of slow decay from wider internet standards contributed to the browsers lack of adoption amongst a rapidly evolving, standards compliant set of Webkit/standards based browsers.

Perhaps, the best news for me is the decision to use the Webkit engine. In some respects it's not the browser necessarily that limits front-end development, but the rendering engine. Spartan now joins the likes of Chrome and Safari in adopting Webkit. To be honest, all browsers should just adopt Webkit so more focus can be applied to generating amazing new content rather than working on x-browser compatibility issues.

Browser Engine
Chrome Webkit (-webkit)
Safari Webkit (-webkit)
Spartan! Webkit
Firefox Gecko (-moz)
Opera Presto/Blink (-o)
Internet Explorer Trident (-ms)