Add ClassNodeElement and allow Analyzer to use cached unimplemented members

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

Index: compiler/java/com/google/dart/compiler/resolver/ClassElementImplementation.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/ClassElementImplementation.java b/compiler/java/com/google/dart/compiler/resolver/ClassElementImplementation.java
index 57547f379b7d46da87cd8ad996e85bc81373ee2a..8b7a9688d3226598925b7737a6d2b883b7c0c534 100644
--- a/compiler/java/com/google/dart/compiler/resolver/ClassElementImplementation.java
+++ b/compiler/java/com/google/dart/compiler/resolver/ClassElementImplementation.java
@@ -22,7 +22,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
 
-class ClassElementImplementation extends AbstractNodeElement implements ClassElement {
+class ClassElementImplementation extends AbstractNodeElement implements ClassNodeElement {
   private InterfaceType type;
   private InterfaceType supertype;
   private InterfaceType defaultClass;
@@ -34,6 +34,7 @@ class ClassElementImplementation extends AbstractNodeElement implements ClassEle
       new AtomicReference<List<InterfaceType>>();
   private final SourceInfo nameLocation;
   private final String declarationNameWithTypeParameter;
+  private List<Element> unimplementedMembers;
 
   // declared volatile for thread-safety
   @SuppressWarnings("unused")
@@ -359,4 +360,14 @@ class ClassElementImplementation extends AbstractNodeElement implements ClassEle
       }
     }
   }
+  
+  @Override
+  public List<Element> getUnimplementedMembers() {
+    return unimplementedMembers;
+  }
+  
+  @Override
+  public void setUnimplementedMembers(List<Element> members) {
+    this.unimplementedMembers = members;
+  }
 }