t = this.sharedSuffix(current, old, minLength - prefixCount);
currentStart += prefixCount;
oldStart += prefixCount;
currentEnd -= suffixCount;
oldEnd -= suffixCount;
if (currentEnd - currentStart == 0 && oldEnd - oldStart == 0)
return [];
if (currentStart == currentEnd) {
var splice = newSplice(currentStart, [], 0);
while (oldStart < oldEnd)
splice.removed.push(old[oldStart++]);
return [splice];
} else if (oldStart == oldEnd)
return [newSplice(currentStart, [], currentEnd - currentStart)];
var ops = this.sp