Oops, the sourceIndex of the documentElement in IE is 1, not 0.

jeresig · jeresig · commit 7421f3428409 · 2009-02-14T17:06:30.000Z
diff --git a/src/selector.js b/src/selector.js
@@ -671,7 +671,7 @@ if ( document.documentElement.compareDocumentPosition ) {
 		}
 		return ret;
 	};
-} else if ( document.documentElement.sourceIndex === 0 ) {
+} else if ( document.documentElement.sourceIndex === 1 ) {
 	sortOrder = function( a, b ) {
 		var ret = a.sourceIndex - b.sourceIndex;
 		if ( ret === 0 ) {

Original file line number	Diff line number	Diff line change
`@@ -671,7 +671,7 @@ if ( document.documentElement.compareDocumentPosition ) {`
`671`	`671`	`}`
`672`	`672`	`return ret;`
`673`	`673`	`};`
`674`		`-} else if ( document.documentElement.sourceIndex === 0 ) {`
	`674`	`+} else if ( document.documentElement.sourceIndex === 1 ) {`
`675`	`675`	`sortOrder = function( a, b ) {`
`676`	`676`	`var ret = a.sourceIndex - b.sourceIndex;`
`677`	`677`	`if ( ret === 0 ) {`