Added support for exports and re-exports.

lib/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.
 
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
 const bool REPORT_EXCESS_RESOLUTION = false;
@@ skipping 365 matching lines @@
 
     libraries['dart:core'] = coreLibrary;
     libraries['dart:coreimpl'] = coreImplLibrary;
 
     assertMethod = jsHelperLibrary.find(const SourceString('assert'));
     identicalFunction = coreLibrary.find(const SourceString('identical'));
 
     initializeSpecialClasses();
   }
 
-  void importCoreLibrary(LibraryElement library) {
+  /**
+   * Lazily loads and returns the [LibraryElement] for the dart:core library.
+   */
+  LibraryElement importCoreLibrary(ImportExportHandler handler) {
     Uri coreUri = new Uri.fromComponents(scheme: 'dart', path: 'core');
     if (coreLibrary === null) {
-      coreLibrary = scanner.loadLibrary(coreUri, null, coreUri);
+      coreLibrary =
+          scanner.loadLibraryInternal(handler, coreUri, null, coreUri);
     }
-    scanner.importLibrary(library,
-                          coreLibrary,
-                          null,
-                          library.entryCompilationUnit);
+    return coreLibrary;
   }
 
-  void patchDartLibrary(LibraryElement library, String dartLibraryPath) {
+  void patchDartLibrary(ImportExportHandler handler,
+                        LibraryElement library, String dartLibraryPath) {
     if (library.isPatched) return;
     Uri patchUri = resolvePatchUri(dartLibraryPath);
     if (patchUri !== null) {
-      patchParser.patchLibrary(patchUri, library);
+      patchParser.patchLibrary(handler, patchUri, library);
     }
   }
 
   void applyContainerPatch(ScopeContainerElement original,
                            Link<Element> patches) {
     while (!patches.isEmpty()) {
       Element patchElement = patches.head;
       Element originalElement = original.localLookup(patchElement.name);
       if (patchElement.isAccessor() && originalElement !== null) {
         if (originalElement.kind !== ElementKind.ABSTRACT_FIELD) {
@@ skipping 563 matching lines @@
  * information in the generated error message.
  */
 bool invariant(Spannable spannable, var condition, {String message: null}) {
   // TODO(johnniwinther): Use [spannable] and [message] to provide better
   // information on assertion errors.
   if (condition is Function){
     condition = condition();
   }
   return spannable != null && condition;
 }