Handle exports being registered before declarations.

sdk/lib/_internal/compiler/implementation/patch_parser.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.
 
 /**
  * This library contains the infrastructure to parse and integrate patch files.
  *
  * Three types of elements can be patched: [LibraryElement], [ClassElement],
  * [FunctionElement]. Patches are introduced in patch libraries which are loaded
  * together with the corresponding origin library. Which libraries that are
@@ skipping 127 matching lines @@
       var patchLibrary = new LibraryElementX(script, null, originLibrary);
       return compiler.withCurrentElement(patchLibrary, () {
         handler.registerNewLibrary(patchLibrary);
         var imports = new LinkBuilder<tree.LibraryTag>();
         compiler.withCurrentElement(patchLibrary.entryCompilationUnit, () {
           // This patches the elements of the patch library into [library].
           // Injected elements are added directly under the compilation unit.
           // Patch elements are stored on the patched functions or classes.
           scanLibraryElements(patchLibrary.entryCompilationUnit, imports);
         });
-        // After scanning declarations, we handle the import tags in the patch.
-        // TODO(lrn): These imports end up in the original library and are in
-        // scope for the original methods too. This should be fixed.
-        compiler.importHelperLibrary(originLibrary);
         // TODO(rnystrom): Remove .toList() here if #11523 is fixed.
         return Future.forEach(imports.toLink().toList(), (tag) {
           return compiler.withCurrentElement(patchLibrary, () {
             return compiler.libraryLoader.registerLibraryFromTag(
                 handler, patchLibrary, tag);
           });
         });
       });
     });
   }
@@ skipping 391 matching lines @@
 
 // TODO(johnniwinther): Add unittest when patch is (real) metadata.
 bool isPatchElement(Element element) {
   // TODO(lrn): More checks needed if we introduce metadata for real.
   // In that case, it must have the identifier "native" as metadata.
   for (Link link = element.metadata; !link.isEmpty; link = link.tail) {
     if (link.head is PatchMetadataAnnotation) return true;
   }
   return false;
 }