anchor.diff:        int classIndex = currentClass;
         // Chase randomly up in class hierarchy.
         while (classParents[classIndex] > 0) {
  -        // TODO(bkonyi): change to use coinFlip()
  -        if (rollDice(2)) {
  +        if (coinFlip()) {
             break;
           }
           classIndex = classParents[classIndex];
  
positive.code:   void emitPreOrPostExpr(int depth, DartType tp, {RhsFilter rhsFilter}) {
      if (tp == DartType.INT) {
        emitParenWrapped(() {
          // TODO(bkonyi): change to use coinFlip()
          bool pre = rollDice(2);
          if (pre) {
            emitPreOrPostOp(tp);
          }
  
negative.code:       if (constructor.isNotEmpty) {
          emit('${tp.name}.${constructor}');
        } else {
          // New is no longer necessary as of Dart 2, but is still supported.
          // Emit a `new` once in a while to ensure it's covered.
          emit('${rollDice(10) ? "new " : ""}${tp.name}');
        }
        emitParenWrapped(() {
          // Iterate over constructor parameters.
  