[IE] Block selection breaks enterBr

[garry.yao]

1. Load the editor with the following content with enterBr:

   <div>
   	line1<br />
   	line2<br />
   	line3</div>
   

2. Fully select first two lines by mouse;
3. Click on "Indent" button;

• Actual Result: All three lines are indented.
• Expected Result: New block (div) created for the first two lines which get indented.

Same problem applies to other block commands like alignment.

[garry.yao]

This's probably due to the mouse selection has result in the following range which includes the the second <br> inside:

<div>
	line1<br />
	line2<br />
	line3</div>

[garry.yao]

IE and Opera are including the the tail <br> when selecting one line.