anchor.diff:        scanner.scanChar(0xFEFF);
         var statements = this.statements(() => _statement(root: true));
         scanner.expectDone();
  +
  +      /// Ensure that all gloal variable assignments produce a variable in this
  +      /// stylesheet, even if they aren't evaluated. See sass/language#50.
  +      statements.addAll(_globalVariables.values.map((declaration) =>
  +          VariableDeclaration(declaration.name,
  +              NullExpression(declaration.expression.span), declaration.span,
  +              guarded: true)));
  +
         return Stylesheet(statements, scanner.spanFrom(start),
             plainCss: plainCss);
       });
  
positive.code:   /// Whether the parser is currently within a parenthesized expression.
    var _inParentheses = false;
  
    /// The silent comment this parser encountered previously.
    @protected
    SilentComment lastSilentComment;
  
negative.code:     }
  
      expectStatementSeparator("variable declaration");
      var declaration = VariableDeclaration(name, value, scanner.spanFrom(start),
          namespace: namespace,
          guarded: guarded,
          global: global,
          comment: precedingComment);
      if (global) _globalVariables.putIfAbsent(name, () => declaration);
      return declaration;
    }
  
    /// Consumes a style rule.
  