xIndex for instertion after location

[GoogleCodeExporter]

Hello!

When you are looking for the end position while something was added to the end 
of the text, then result will be the end of the new text. Here is a test:
    assertEquals(3, dmp.diff_xIndex([[DIFF_EQUAL, 'foo'], [DIFF_INSERT, 'bar']], 3));
The result will be 6.

My understanding of locations within text is that it's just like a cursor. For 
example:
    |foo - position 0
    f|oo - position 1
    fo|o - position 2
    foo| - position 3

I've tried to fix it by myself and have changed > comparison to >= in 
https://code.google.com/p/google-diff-match-patch/source/browse/trunk/javascript
/diff_match_patch_uncompressed.js#1199
but it's actually breaks the last test for patchApply, so I'm doubting about my 
understanding of locations within text. So, can you make it clear what is that 
location in xIndex method?

By the way, there is a small bug in the doc example for xIndex:
    e.g. 'The cat' vs 'The big cat', 1->1, 5->8
There was 4 chars inserted ("big "), so 5 should became 9.

Original issue reported on code.google.com by grigory.kalabin on 29 Apr 2014 at 3:05