code: int getTrailCCFromCompYesAndZeroCC(CharSequence s, int cpStart, int cpLimit) {
          int c;
          if(cpStart==(cpLimit-1)) {
              c=s.charAt(cpStart);
          } else {
              c=Character.codePointAt(s, cpStart);
          }
          int prevNorm16=getNorm16(c);
          if(prevNorm16<=minYesNo) {
              return 0;  // yesYes and Hangul LV/LVT have ccc=tccc=0
          } else {
              return extraData.charAt(prevNorm16)>>8;  // tccc from yesNo
          }
      }
docs: requires that the [cpStart..cpLimit[ character passes isCompYesAndZeroCC()