Report internal error when an exported library isn't loaded.

pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

 // Copyright (c) 2017, 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.
 
 // NOTE: THIS FILE IS GENERATED. DO NOT EDIT.
 //
 // Instead modify 'pkg/front_end/messages.yaml' and run
 // 'pkg/front_end/tool/_fasta/generate_messages.dart' to update.
 
 part of fasta.codes;
@@ skipping 1434 matching lines @@
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 Message _withArgumentsInternalProblemConstructorNotFound(
     String name, Uri uri_) {
   String uri = relativizeUri(uri_);
   return new Message(codeInternalProblemConstructorNotFound,
       message: """No constructor named '$name' in '$uri'.""",
       arguments: {'name': name, 'uri': uri_});
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(Uri uri_, Uri uri2_)>
+    templateInternalProblemExportedLibraryNotLoaded =
+    const Template<Message Function(Uri uri_, Uri uri2_)>(
+        messageTemplate:
+            r"""The library '#uri' isn't loaded, but '#uri2' exports it.""",
+        withArguments: _withArgumentsInternalProblemExportedLibraryNotLoaded);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(Uri uri_, Uri uri2_)>
+    codeInternalProblemExportedLibraryNotLoaded =
+    const Code<Message Function(Uri uri_, Uri uri2_)>(
+  "InternalProblemExportedLibraryNotLoaded",
+  templateInternalProblemExportedLibraryNotLoaded,
+);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsInternalProblemExportedLibraryNotLoaded(
+    Uri uri_, Uri uri2_) {
+  String uri = relativizeUri(uri_);
+  String uri2 = relativizeUri(uri2_);
+  return new Message(codeInternalProblemExportedLibraryNotLoaded,
+      message: """The library '$uri' isn't loaded, but '$uri2' exports it.""",
+      arguments: {'uri': uri_, 'uri2': uri2_});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeInternalProblemExtendingUnmodifiableScope =
     messageInternalProblemExtendingUnmodifiableScope;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageInternalProblemExtendingUnmodifiableScope =
     const MessageCode("InternalProblemExtendingUnmodifiableScope",
         message: r"""Can't extend an unmodifiable scope.""");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeInternalProblemMissingContext =
@@ skipping 1665 matching lines @@
         r"""'yield' can't be used as an identifier in 'async', 'async*', or 'sync*' methods.""");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Code<Null> codeYieldNotGenerator = messageYieldNotGenerator;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const MessageCode messageYieldNotGenerator = const MessageCode(
     "YieldNotGenerator",
     dart2jsCode: "*ignored*",
     message: r"""'yield' can only be used in 'sync*' or 'async*' methods.""");