anchor.diff:    js_ast.Expression visitMapConstant(MapConstant node) {
       var entries = [
         for (var e in node.entries) ...[
  -        _visitConstant(e.key),
  -        _visitConstant(e.value),
  +        visitConstant(e.key),
  +        visitConstant(e.value),
         ],
       ];
       return _emitConstMap(node.keyType, node.valueType, entries);
  
positive.code: import 'property_model.dart';
  import 'type_table.dart';
  
  class ProgramCompiler extends Object
      with SharedCompiler<Library, Class, InterfaceType, FunctionNode>
      implements
          StatementVisitor<js_ast.Statement>,
          ExpressionVisitor<js_ast.Expression>,
          DartTypeVisitor<js_ast.Expression>,
          ConstantVisitor<js_ast.Expression> {
    final SharedCompilerOptions _options;
  
    /// Maps a library URI import, that is not in [_libraries], to the
  
negative.code:     // Order will be changed as needed so the resulting code can execute.
      // This is done by forward declaring items.
      libraries.forEach(_emitLibrary);
  
      // This can cause problems if it's ever true during the SDK build, as it's
      // emitted before dart.defineLazy.
      if (_constLazyAccessors.isNotEmpty) {
        var constTableBody = runtimeStatement(
            'defineLazy(#, { # })', [_constTable, _constLazyAccessors]);
        moduleItems.insert(_constTableInsertionIndex, constTableBody);
        _constLazyAccessors.clear();
      }
  
      moduleItems.addAll(afterClassDefItems);
      afterClassDefItems.clear();
  