Retain elements a finer granularity than library.

dart/sdk/lib/_internal/compiler/implementation/dart2js.dart

 // Copyright (c) 2013, 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.cmdline;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math' as math;
 
@@ skipping 241 matching lines @@
     new OptionHandler(r'--help|/\?|/h', (_) => wantHelp = true),
     new OptionHandler('--package-root=.+|-p.+', setPackageRoot),
     new OptionHandler('--disallow-unsafe-eval', passThrough),
     new OptionHandler('--analyze-all', passThrough),
     new OptionHandler('--analyze-only', setAnalyzeOnly),
     new OptionHandler('--analyze-signatures-only', passThrough),
     new OptionHandler('--disable-native-live-type-analysis', passThrough),
     new OptionHandler('--categories=.*', setCategories),
     new OptionHandler('--global-js-name=.*', checkGlobalName),
     new OptionHandler('--disable-type-inference', passThrough),
+    new OptionHandler('--terse', passThrough),
 
     // The following two options must come last.
     new OptionHandler('-.*', (String argument) {
       helpAndFail('Error: Unknown option "$argument".');
     }),
     new OptionHandler('.*', (String argument) {
       arguments.add(nativeToUriPath(argument));
     })
   ];
 
@@ skipping 221 matching lines @@
 
   --suppress-warnings
     Do not display any warnings.
 
   --suppress-hints
     Do not display any hints.
 
   --enable-diagnostic-colors
     Add colors to diagnostic messages.
 
+  --terse
+    Emit diagnostics without suggestions for how to get rid of the diagnosed
+    problems.
+
 The following options are only used for compiler development and may
 be removed in a future version:
 
   --output-type=dart
     Output Dart code instead of JavaScript.
 
   --throw-on-error
     Throw an exception if a compile-time error is detected.
 
   --library-root=<directory>
@@ skipping 60 matching lines @@
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }
 
 void main() {
   mainWithErrorHandler(new Options());
 }