anchor.diff:      context.resolveCompilationUnit(source, element);
       _buildLibraryBody(element, node);
       for (var unit in element.units) {
  +      LineInfo lines;
         for (var error in context.computeErrors(unit.source)) {
           if (error.errorCode is CompileTimeErrorCode ||
               error.errorCode is ParserErrorCode ||
  
positive.code:             // Ignore warnings about 'const' factories in the patched SDK.
              continue;
            }
            errors.add(error);
          }
        }
      }
  
negative.code:     });
    }
  
    String formatErrorMessage(
        AnalysisError error, String filename, LineInfo lines) {
      var location = lines.getLocation(error.offset);
      return '[error] ${error.message} ($filename, '
          'line ${location.lineNumber}, '
          'col ${location.columnNumber})';
    }
  
    void ensureLibraryIsLoaded(ast.Library node) {
      if (node.isLoaded) return;
      var source = context.sourceFactory.forUri2(node.importUri);
  