IE9 doesn't like the Comment and Text nodeValue shims

[Shawn Allen]

I'm running aight v2 tests on IE8 and 9 (not pushed yet, but will be soon), and IE9 is failing as a result of the Text#nodeValue shim. I've followed this down into the guts of ie8.js and found that the fallback descriptors are undefined in commonTextContent() for both the Text#nodeValue and Comment#nodeValue, which causes the shimmed property getter and setter to throw an exception when the accessors are called, e.g. Unable to get value of the property 'get': object is null or undefined. My patch just returns early from commonTextContent() when the fallback descriptor is undefined, but this doesn't seem like quite the right thing to do.

I know that ie8.js is intended for IE8, but I need a lot of those shims in aight for IE9 support as well. In this specific case, though, IE9's native Text#nodeValue implementation works. So, should I fork this repo and make some aight-specific patches for IE9 compatibility, or would you prefer to do some light-weight feature detection that ensures it'll just work in IE9?