function addMappingWithCode(mapping, code) {
        if (mapping === null || mapping.source === undefined) {
          node.add(code);
        } else {
          node.add(new SourceNode(mapping.originalLine,
                                  mapping.originalColumn,
                                  mapping.source,
                                  code,
                                  mapping.name));
        }
      }
Creates a SourceNode from generated code and a SourceMapConsumer.

@param aGeneratedCode The generated code
@param aSourceMapConsumer The SourceMap for the generated code