Version 0.4.7.3 .

editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/resolver/TypeResolverVisitor.java

 /*
  * Copyright (c) 2013, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  * 
  * http://www.eclipse.org/legal/epl-v10.html
  * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
@@ skipping 689 matching lines @@
       String dynamicKeyword = Keyword.DYNAMIC.getSyntax();
       boolean[] detectedRepeatOnIndex = new boolean[typeNames.length];
       for (int i = 0; i < detectedRepeatOnIndex.length; i++) {
         detectedRepeatOnIndex[i] = false;
       }
       for (int i = 0; i < typeNames.length; i++) {
         TypeName typeName = typeNames[i];
         String name = typeName.getName().getName();
         if (name.equals(dynamicKeyword)) {
           reportError(CompileTimeErrorCode.IMPLEMENTS_DYNAMIC, typeName);
-        } else if (typeName.getName().getElement().equals(classElement)) {
-          reportError(CompileTimeErrorCode.IMPLEMENTS_SELF, typeName, name);
+        } else {
+          Element element = typeName.getName().getElement();
+          if (element != null && element.equals(classElement)) {
+            reportError(CompileTimeErrorCode.IMPLEMENTS_SELF, typeName, name);
+          }
         }
         if (!detectedRepeatOnIndex[i]) {
           for (int j = i + 1; j < typeNames.length; j++) {
+            Element element = typeName.getName().getElement();
             TypeName typeName2 = typeNames[j];
-            String name2 = typeName2.getName().getName();
-            if (typeName.getName().getElement().equals(typeName2.getName().getElement())) {
+            Identifier identifier2 = typeName2.getName();
+            String name2 = identifier2.getName();
+            Element element2 = identifier2.getElement();
+            if (element != null && element.equals(element2)) {
               detectedRepeatOnIndex[j] = true;
               reportError(CompileTimeErrorCode.IMPLEMENTS_REPEATED, typeName2, name2);
             }
           }
         }
       }
       if (classElement != null) {
         classElement.setInterfaces(interfaceTypes);
       }
     }
@@ skipping 90 matching lines @@
     if (!namedParameterTypes.isEmpty()) {
       functionType.setNamedParameterTypes(namedParameterTypes);
     }
     if (returnType == null) {
       functionType.setReturnType(dynamicType);
     } else {
       functionType.setReturnType(returnType.getType());
     }
   }
 }