HeapSnapshot: sometimes profiler fails to show next chunk of data.

It happens when sort does sort for the range which 
has a number of nodes that are equal in term of
current comparator. In that case the sort algorythm hits into 
v8 max stack size limit 10k frames. We can avoid this if we compare index values 
of the nodes as the last resort.

BUG=none

Review URL: https://chromiumcodereview.appspot.com/23591037

git-svn-id: svn://svn.chromium.org/blink/trunk@157668 bbb929c8-8fbe-4397-9dbb-9b2b20218538