use Source.isInSystemLibrary

lib/src/codegen/js_module_item_order.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection' show HashMap;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 
 import '../compiler.dart' show corelibOrder;
@@ skipping 194 matching lines @@
     }
   }
 
   bool libraryIsLoaded(LibraryElement library) {
     assert(library != _currentLibrary);
 
     // DynamicElementImpl has no library.
     if (library == null) return true;
 
     // The SDK is a special case: we optimize the order to prevent laziness.
-    if (_isDartUri(library)) {
+    if (library.source.isInSystemLibrary) {
       // SDK is loaded before non-SDK libraries
-      if (!_isDartUri(_currentLibrary)) return true;
+      if (!_currentLibrary.source.isInSystemLibrary) return true;
 
       // Compute the order of both SDK libraries. If unknown, assume it's after.
       var order = corelibOrder.indexOf(library.source.uri);
       if (order == -1) order = corelibOrder.length;
 
       var currentOrder = corelibOrder.indexOf(_currentLibrary.source.uri);
       if (currentOrder == -1) currentOrder = corelibOrder.length;
 
       // If the dart:* library we are currently compiling is loaded after the
       // class's library, then we know the class is available.
       if (order != currentOrder) return currentOrder > order;
 
       // If we don't know the order of the class's library or the current
       // library, do the normal cycle check. (Not all SDK libs are cycles.)
     }
 
     return !_inLibraryCycle(library);
   }
 
   /// Returns true if [library] depends on the [currentLibrary] via some
   /// transitive import.
   bool _inLibraryCycle(LibraryElement library) {
     // SDK libs don't depend on things outside the SDK.
     // (We can reach this via the recursive call below.)
-    if (_isDartUri(library) && !_isDartUri(_currentLibrary)) return false;
+    if (library.source.isInSystemLibrary &&
+        !_currentLibrary.source.isInSystemLibrary) return false;
 
     var result = _libraryCycleMemo[library];
     if (result != null) return result;
 
     result = library == _currentLibrary;
     _libraryCycleMemo[library] = result;
     for (var e in library.imports) {
       if (result) break;
       result = _inLibraryCycle(e.importedLibrary);
     }
     for (var e in library.exports) {
       if (result) break;
       result = _inLibraryCycle(e.exportedLibrary);
     }
     return _libraryCycleMemo[library] = result;
   }
-
-  /// Returns whether this is a library imported with 'dart:' URI.
-  ///
-  /// This is similar to [LibraryElement.isInSdk], but checking the URI instead
-  /// of the library naming convention, because the URI is reliable.
-  static bool _isDartUri(LibraryElement e) => e.source.uri.scheme == 'dart';
 }