Tweak the intraline difference heuristics

We had a few cases where the intraline difference was showing us
something confusing, like replacing characters in a common word
with other characters from a different word.

A bit of shifting the offsets after collapsing neighboring edits
resolves this nicely.

Change-Id: Ic947912277d96bf78afbc9831fb16e4b64e31fb1
Signed-off-by: Shawn O. Pearce <sop@google.com>
3 files changed