Don't emit unused hints when there are compilation errors.

dart/sdk/lib/_internal/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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 1069 matching lines @@
       libraries.forEach(
           (_, lib) => fullyEnqueueLibrary(lib, enqueuer.resolution));
     }
     // Elements required by enqueueHelpers are global dependencies
     // that are not pulled in by a particular element.
     backend.enqueueHelpers(enqueuer.resolution, globalDependencies);
     resolveLibraryMetadata();
     processQueue(enqueuer.resolution, main);
     enqueuer.resolution.logSummary(log);
 
+    if (compilationFailed) return;
     if (analyzeOnly) {
       if (!analyzeAll) {
         // No point in reporting unused code when [analyzeAll] is true: all
         // code is artificially used.
         reportUnusedCode();
       }
       return;
     }
-    if (compilationFailed) return;
     assert(main != null);
     phase = PHASE_DONE_RESOLVING;
 
     // TODO(ahe): Remove this line. Eventually, enqueuer.resolution
     // should know this.
     world.populate();
     // Compute whole-program-knowledge that the backend needs. (This might
     // require the information computed in [world.populate].)
     backend.onResolutionComplete();
 
@@ skipping 569 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }