Consider special handler for style attribute bindings

[sorvell]

When a binding in the style attribute causes the attribute to be re-written, any settings to style properties are lost. Perhaps this could be fixed by having style bindings directly update style properties rather than the attribute.

Here's an example, note that the box unexpectedly jumps up when the background data changes:

http://jsbin.com/matef/3/edit

[frankiefu]

In paper-progress we do style attribute binding to change the width:

<div id="activeProgress" style="width: {{ratio}}%;"></div>

An user wants to change the style of paper-progress from javascript:

this.$.prog.querySelector("::shadow #activeProgress").style.backgroundColor = 'red';

This will not work because binding in the style attribute causes the attribute to be re-written. I can workaround this in paper-progress but I just want to make a note here.