Handle exports being registered before declarations.

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

Index: sdk/lib/_internal/compiler/implementation/patch_parser.dart
diff --git a/sdk/lib/_internal/compiler/implementation/patch_parser.dart b/sdk/lib/_internal/compiler/implementation/patch_parser.dart
index 88da806730fb8fa18cd3b4540ea65a659e09234a..fcd0be208fa1f202796ac5af746d0697d7fdd3cf 100644
--- a/sdk/lib/_internal/compiler/implementation/patch_parser.dart
+++ b/sdk/lib/_internal/compiler/implementation/patch_parser.dart
@@ -145,10 +145,6 @@ class PatchParserTask extends leg.CompilerTask {
           // 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, () {