对Internet Explorer的W3C DOM范围实现。

W3C DOM Ranges for IE IERange is a feature-complete implementation of W3C [DOM Ranges](http://www.w3.org/TR/DOM-Level-2-Traversal-Range/ranges.html) for Internet Explorer, allowing users to write one cross-browser version of their range manipulation code. Internet Explorer 6–8 supports text ranges and document editing, but it does not support one of the more useful features when it comes to DOM manipulation, DOM Ranges. Internet Explorer has a native implementation of its own "Text Ranges", which operate solely on text content and is not compatible with the W3C version. Additionally, IE supports a document.selection object which is not compatible with other browsers" implementations. IERange emulates W3C ranges on top of the browser"s native implementation. Test Y