Load builtin helper libraries on demand.

sdk/lib/_internal/compiler/implementation/compiler.dart

 // Copyright (c) 2012, 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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 227 matching lines @@
   ClassElement defaultSuperclass(ClassElement element) => compiler.objectClass;
 
   bool isDefaultNoSuchMethodImplementation(Element element) {
     assert(element.name == Compiler.NO_SUCH_METHOD);
     ClassElement classElement = element.getEnclosingClass();
     return classElement == compiler.objectClass;
   }
 
   void registerStaticUse(Element element, Enqueuer enqueuer) {}
 
-  void onLibraryScanned(LibraryElement library, Uri uri) {}
+  void onLibraryLoaded(LibraryElement library, Uri uri) {}
 
   void registerMetadataInstantiatedType(DartType type, TreeElements elements) {}
   void registerMetadataStaticUse(Element element) {}
   void registerMetadataGetOfStaticFunction(FunctionElement element) {}
 
   /// Called by [MirrorUsageAnalyzerTask] after it has merged all @MirrorsUsed
   /// annotations. The arguments corresponds to the unions of the corresponding
   /// fields of the annotations.
   void registerMirrorUsage(Set<String> symbols,
                            Set<Element> targets,
@@ skipping 488 matching lines @@
     }
     return !compilationFailed;
   }
 
   bool hasIsolateSupport() => isolateLibrary != null;
 
   /**
    * This method is called before [library] import and export scopes have been
    * set up.
    */
-  void onLibraryScanned(LibraryElement library, Uri uri) {
+  void onLibraryLoaded(LibraryElement library, Uri uri) {
     if (dynamicClass != null) {
       // When loading the built-in libraries, dynamicClass is null. We
       // take advantage of this as core imports js_helper and sees [dynamic]
       // this way.
       withCurrentElement(dynamicClass, () {
         library.addToScope(dynamicClass, this);
       });
     }
     if (uri == new Uri(scheme: 'dart', path: 'mirrors')) {
       mirrorsLibrary = library;
       mirrorSystemClass =
           findRequiredElement(library, const SourceString('MirrorSystem'));
       mirrorsUsedClass =
           findRequiredElement(library, const SourceString('MirrorsUsed'));
     } else if (uri == new Uri(scheme: 'dart', path: '_collection-dev')) {
       symbolImplementationClass =
           findRequiredElement(library, const SourceString('Symbol'));
     } else if (uri == new Uri(scheme: 'dart', path: 'async')) {
       deferredLibraryClass =
           findRequiredElement(library, const SourceString('DeferredLibrary'));
+    } else if (isolateHelperLibrary == null
+               && (uri == new Uri(scheme: 'dart', path: '_isolate_helper'))) {
+      isolateHelperLibrary = scanBuiltinLibrary('_isolate_helper');
+    } else if (foreignLibrary == null
+               && (uri == new Uri(scheme: 'dart', path: '_foreign_helper'))) {
+      foreignLibrary = scanBuiltinLibrary('_foreign_helper');
     }
-    backend.onLibraryScanned(library, uri);
+    backend.onLibraryLoaded(library, uri);
   }
 
   Element findRequiredElement(LibraryElement library, SourceString name) {
     var element = library.find(name);
     if (element == null) {
       internalErrorOnElement(
           library,
           'The library "${library.canonicalUri}" does not contain required '
           'element: ${name.slowToString()}');
       }
@@ skipping 88 matching lines @@
     if (_filledListConstructor != null) return _filledListConstructor;
     Selector callConstructor = new Selector.callConstructor(
         const SourceString("filled"), listClass.getLibrary());
     return _filledListConstructor =
         listClass.lookupConstructor(callConstructor);
   }
 
   void scanBuiltinLibraries() {
     jsHelperLibrary = scanBuiltinLibrary('_js_helper');
     interceptorsLibrary = scanBuiltinLibrary('_interceptors');
-    foreignLibrary = scanBuiltinLibrary('_foreign_helper');
-    isolateHelperLibrary = scanBuiltinLibrary('_isolate_helper');
-
     assertMethod = jsHelperLibrary.find(const SourceString('assertHelper'));
     identicalFunction = coreLibrary.find(const SourceString('identical'));
 
     initializeSpecialClasses();
 
     functionClass.ensureResolved(this);
     functionApplyMethod =
         functionClass.lookupLocalMember(const SourceString('apply'));
     jsInvocationMirrorClass.ensureResolved(this);
     invokeOnMethod = jsInvocationMirrorClass.lookupLocalMember(INVOKE_ON);
@@ skipping 624 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }