anchor.diff:      String text_delete = '';
       String text_insert = '';
       int commonlength;
  +    int start;
  +    int end;
       while (pointer < diffs.length) {
         switch (diffs[pointer].operation) {
           case DIFF_INSERT:
  
positive.code:       }
        Patch bigpatch = patches[x];
        // Remove the big old patch.
        patches.removeRange(x--, 1);
        int start1 = bigpatch.start1;
        int start2 = bigpatch.start2;
        String precontext = '';
  
negative.code:             patch.length2 += diff_text.length;
              start2 += diff_text.length;
              patch.diffs.add(bigpatch.diffs[0]);
              bigpatch.diffs.removeAt(0);
              empty = false;
            } else if (diff_type == DIFF_DELETE && patch.diffs.length == 1
                && patch.diffs[0].operation == DIFF_EQUAL
  