anchor.diff:          try {
             _promoteManager.enterScope();
             try {
  -            _propagateTrueState(leftOperand);
               // Type promotion.
               _promoteTypes(leftOperand);
               _clearTypePromotionsIfPotentiallyMutatedIn(leftOperand);
  
positive.code:     if (elseStatement != null) {
        _overrideManager.enterScope();
        try {
          _propagateFalseState(condition);
          visitStatementInScope(elseStatement);
        } finally {
          elseOverrides = _overrideManager.captureLocalOverrides();
  
negative.code:   void visitAssertStatement(AssertStatement node) {
      InferenceContext.setType(node.condition, typeProvider.boolType);
      super.visitAssertStatement(node);
    }
  
    @override
  