anchor.diff:  
     void visitString(SassString string) {
       if (_quote && string.hasQuotes) {
  -      _visitString(string.text);
  +      _visitQuotedString(string.text);
       } else {
  -      // TODO: write this character-by-character.
  -      _buffer.write(string.text.replaceAll("\n", " "));
  -    }
  -  }
  -
  -  /// Writes [string] to [_buffer].
  +      _visitUnquotedString(string.text);
  +    }
  +  }
  +
  +  /// Writes a quoted string with [string] contents to [_buffer].
     ///
     /// By default, this detects which type of quote to use based on the contents
     /// of the string. If [forceDoubleQuote] is `true`, this always uses a double
     /// quote.
  -  void _visitString(String string, {bool forceDoubleQuote: false}) {
  +  void _visitQuotedString(String string, {bool forceDoubleQuote: false}) {
       var includesSingleQuote = false;
       var includesDoubleQuote = false;
   
  
positive.code:       _buffer.writeCharCode(quote);
        _buffer.write(buffer);
        _buffer.writeCharCode(quote);
      }
    }
  
  
negative.code:             buffer.writeCharCode($backslash);
              buffer.writeCharCode($double_quote);
            } else if (includesSingleQuote) {
              _visitQuotedString(string, forceDoubleQuote: true);
              return;
            } else {
              includesDoubleQuote = true;
  