Additional fix for issue 2155

compiler/java/com/google/dart/compiler/resolver/ClassScope.java

Index: compiler/java/com/google/dart/compiler/resolver/ClassScope.java
===================================================================
--- compiler/java/com/google/dart/compiler/resolver/ClassScope.java	(revision 8661)
+++ compiler/java/com/google/dart/compiler/resolver/ClassScope.java	(working copy)
@@ -6,6 +6,9 @@
 
 import com.google.dart.compiler.type.InterfaceType;
 
+import java.util.HashSet;
+import java.util.Set;
+
 /**
  * Lexical scope corresponding to a class body.
  */
@@ -24,18 +27,23 @@
 
   @Override
   public Element findElement(LibraryElement inLibrary, String name) {
+    return findElement(inLibrary, name, new HashSet<ClassElement>());
+  }
+
+  protected Element findElement(LibraryElement inLibrary, String name, Set<ClassElement> examinedTypes) {
     Element element = super.findElement(inLibrary, name);
     if (element != null) {
       return element;
     }
+    examinedTypes.add(classElement);
     InterfaceType superclass = classElement.getSupertype();
     if (superclass != null) {
       Element enclosing = superclass.getElement().getEnclosingElement();
       ClassElement superclassElement = superclass.getElement();
-      if (superclassElement != classElement) {
+      if (!examinedTypes.contains(superclassElement)) {
         ClassScope scope = new ClassScope(superclassElement,
                                           new Scope("library", (LibraryElement) enclosing));
-        element = scope.findElement(inLibrary, name);
+        element = scope.findElement(inLibrary, name, examinedTypes);
         switch (ElementKind.of(element)) {
           case TYPE_VARIABLE:
             return null;
@@ -49,10 +57,10 @@
     for (InterfaceType supertype : classElement.getInterfaces()) {
       Element enclosing = supertype.getElement().getEnclosingElement();
       ClassElement superclassElement = supertype.getElement();
-      if (superclassElement != classElement) {
+      if (!examinedTypes.contains(superclassElement)) {
         ClassScope scope = new ClassScope(superclassElement,
                                           new Scope("library", (LibraryElement) enclosing));
-        element = scope.findElement(inLibrary, name);
+        element = scope.findElement(inLibrary, name, examinedTypes);
         if (element != null) {
           return element;
         }