Make CSS transplantation work in IE10

When ResourceLoader creates synthetic <style> nodes,
it does that using code like this in IE:

style = document.createElement( 'style' );
head.appendChild( style );
style.styleSheet.cssText = text;

The usual strategy of appending a text node to the <style>
node doesn't appear work in IE. However, setting .cssText this
way means that a TextNode is not created in the DOM
in IE10 (but it is in IE11).

So, as a fallback, look at styleSheets[i].cssText if
styleNode.textContent is empty.

Change-Id: I6d3bfae6630b639933eaf5e7ac438e35e04e9548
Make the background reset for dialogs in Apex work in IE10

background: transparent; and background-color: transparent;
should behave the same, but the former is ignored by IE10.

Also add background-image: none; to compensate for the fact
that we're no longer wiping out all other background-*
properties with background: transparent;

Change-Id: Id776cd6fda8f72ce989cea282a9f6b4ddc21c827