Line breaks are lost when enter mode is br

[wwalc]

Confirmed in Firefox 3.6.13, Safari and Opera.

Steps to reproduce

1. Open _samples/enterkey.html
2. Set enter mode to BR
3. switch to source mode, paste the following:

   <hr />
   <br />
   <br />
   <br />
   

4. Switch to wysiwyg and back
5. Result:

   <hr />
   <br />
   

6. Two line breaks are lost whenever user switches to source mode and back

Regression introduced with [5750].

Note that the real problem in #5293 was unwanted line break in a "supposed to be empty" document so that developers could detect whether user typed something to create a page or not. It was not a problem with an extra line break at the end of the document with some real content.

[garry.yao]

Actually a re-fix of #5293, in fact the original ticket had been overcomplicated.

[Saare]

Please also remove what's in the brackets in line 403 inside htmlparser/fragment.js.

[garry.yao]

Fixed with [6458].