Theme Customizer: IE 8/9 compatibility

[ocean90]

I found some issues with the theme customizer in IE 8 and IE 9.

#1: IE 8 - Header image preview

There is an issue with the small header image preview in the sidebar:

#2: IE 8 - Iframe Preview doesn't load/render html5.js

Not sure what is going on here. It happens for example with the Twenty Eleven theme, see ​http://cl.ly/GHjI. Seems like IE 8 doesn't like html5.js in an iframe.

#3: IE 8 and IE 9 - No preview for background color (sometimes)

Scenario:

• Active Theme: Twenty Ten
• Open the customize screen for Twenty Elven
• Change the background color
• Expected: Color changes.

But it doesn't show the new color. (Workaround: Change the header text color and the background color will be updated too.)

#4: IE 8 and IE 9 - Links inside the iframe

Clicking on a link in the preview iframe loads the active theme with the Toolbar and your will lost all your preview settings. See ​http://cl.ly/GGev.