Use DiagnosticMessage in MockCompiler.

pkg/compiler/lib/src/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.
 
 library dart2js.compiler_base;
 
 import 'dart:async' show
     EventSink,
     Future;
 
@@ skipping 1658 matching lines @@
         break;
       }
     }
     lastDiagnosticWasFiltered = false;
     reportDiagnostic(message, infos, kind);
   }
 
   void reportDiagnostic(DiagnosticMessage message,
                         List<DiagnosticMessage> infos,
                         api.Diagnostic kind) {
+    if (kind == api.Diagnostic.ERROR ||
+        kind == api.Diagnostic.CRASH ||
+        (options.fatalWarnings &&
+         kind == api.Diagnostic.WARNING)) {
+      compiler.compilationFailed = true;
+    }
     compiler.reportDiagnostic(message, infos, kind);
   }
 
   /**
    * Perform an operation, [f], returning the return value from [f].  If an
    * error occurs then report it as having occurred during compilation of
    * [element].  Can be nested.
    */
   withCurrentElement(Element element, f()) {
     Element old = currentElement;
@@ skipping 364 matching lines @@
     if (_otherDependencies == null) {
       _otherDependencies = new Setlet<Element>();
     }
     _otherDependencies.add(element.implementation);
   }
 
   Iterable<Element> get otherDependencies {
     return _otherDependencies != null ? _otherDependencies : const <Element>[];
   }
 }