Reinsert (and test) handling of exceptions from user code.

pkg/compiler/lib/src/library_loader.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.
 
 library dart2js.library_loader;
 
 import 'dart:async';
 
 import 'common/names.dart' show Uris;
 import 'common/tasks.dart' show CompilerTask;
@@ skipping 327 matching lines @@
       if (reusedLibraries != null) {
         reusedLibraries.forEach(mapLibrary);
       }
     });
   }
 
   Future resetAsync(Future<bool> reuseLibrary(LibraryElement library)) {
     return measure(() {
       assert(currentHandler == null);
 
-      wrapper(lib) => reuseLibrary(lib).then((reuse) => reuse ? lib : null);
+      Future<LibraryElement> wrapper(LibraryElement library) {
+        try {
+          return reuseLibrary(library)
+              .then((bool reuse) => reuse ? library : null);
+        } catch (exception, trace) {
+          reporter.onCrashInUserCode(
+              'Uncaught exception in reuseLibrary', exception, trace);
+          rethrow;
+        }
+      }
+
       List<Future<LibraryElement>> reusedLibrariesFuture =
           // TODO(sigmund): make measurements separate from compiler
           compiler.reuseLibraryTask.measure(
               () => libraryCanonicalUriMap.values.map(wrapper).toList());
 
       return Future
           .wait(reusedLibrariesFuture)
           .then((List<LibraryElement> reusedLibraries) {
         resetImplementation(reusedLibraries.where((e) => e != null));
       });
@@ skipping 1105 matching lines @@
   /// Called after a request to load a library. The [results] will include all
   /// transitive libraries loaded as a result of the initial request.
   Future onLibrariesLoaded(LoadedLibraries results);
 
   /// Called whenever a library element is created.
   void onLibraryCreated(LibraryElement library);
 
   /// Called whenever a library is scanned from a script file.
   Future onLibraryScanned(LibraryElement library, LibraryLoader loader);
 }