Load Apple.com and zoom in/out. Notice that the search icon in the search field at the top right doesn't zoom.
(In reply to comment #0) > Load Apple.com and zoom in/out. Notice that the search icon in the search field at the top right doesn't zoom. Page scaling also doesn't propagate into shadow DOM!
(In reply to comment #1) > Page scaling also doesn't propagate into shadow DOM! Nope... but it should! :)
I must request "the beef" in this particular case. Where is it? :) apple.com doesn't use input[type=search]. The reason the icon doesn't scale is because it's a background image, applied using CSS. Also, take a look at this: http://jsfiddle.net/5f5K6/ As you can see, zoom definitely propagates into shadow DOM (look at the spin button). Also, zoom in and out -- everything works! :)
Apparently what I thought was going on wasn't what was going on (some refactored code broke my local test code and caused strangeness). Sorry.