Adjust fallback top/left to just be 0 for disconnected DOM nodes. Fol…

…low-up to cf672a2, thanks to @jitter for the catch.

src/offset.js

@@ -25,7 +25,7 @@ if ( "getBoundingClientRect" in document.documentElement ) {
 			box = elem.getBoundingClientRect();
 
 		} catch(e) {
-			box = { top: elem.offsetTop, left: elem.offsetLeft };
+			box = { top: 0, left: 0 };
 		}
 
 		var doc = elem.ownerDocument,