Version 0.4.7.3 .

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

Index: editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/resolver/TypeResolverVisitor.java
===================================================================
--- editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/resolver/TypeResolverVisitor.java	(revision 21601)
+++ editor/tools/plugins/com.google.dart.engine/src/com/google/dart/engine/internal/resolver/TypeResolverVisitor.java	(working copy)
@@ -707,14 +707,20 @@
         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);
             }