Fix field-accesses for private fields that were "shadowed" by other private fields.

lib/compiler/implementation/elements/elements.dart

Index: lib/compiler/implementation/elements/elements.dart
diff --git a/lib/compiler/implementation/elements/elements.dart b/lib/compiler/implementation/elements/elements.dart
index 53cf714a52f61cda386d2358ab8bb86f53f85283..778084f1ac497624543c7427eeb4448360e779c7 100644
--- a/lib/compiler/implementation/elements/elements.dart
+++ b/lib/compiler/implementation/elements/elements.dart
@@ -1059,13 +1059,22 @@ class ClassElement extends ScopeContainerElement
   }
 
   /**
-  * Lookup super members for the class. This will ignore constructors.
+   * Lookup super members for the class. This will ignore constructors.
    */
   Element lookupSuperMember(SourceString memberName) {
+    return lookupSuperMemberInLibrary(memberName, getLibrary());
+  }
+
+  /**
+   * Lookup super members for the class that is accessible in [library].
+   * This will ignore constructors.
+   */
+  Element lookupSuperMemberInLibrary(SourceString memberName,
+                                     LibraryElement library) {
     bool isPrivate = memberName.isPrivate();
     for (ClassElement s = superclass; s != null; s = s.superclass) {
       // Private members from a different library are not visible.
-      if (isPrivate && getLibrary() !== s.getLibrary()) continue;
+      if (isPrivate && library !== s.getLibrary()) continue;
       Element e = s.lookupLocalMember(memberName);
       if (e === null) continue;
       // Static members are not inherited.
@@ -1094,6 +1103,24 @@ class ClassElement extends ScopeContainerElement
   }
 
   /**
+   * Find the first member in the class chain with the given [selector].
+   *
+   * This method is NOT to be used for resolving
+   * unqualified sends because it does not implement the scoping
+   * rules, where library scope comes before superclass scope.
+   */
+  Element lookupSelector(Selector selector) {
+    SourceString memberName = selector.name;
+    LibraryElement library = selector.library;
+    Element localMember = lookupLocalMember(memberName);
+    if (localMember != null &&
+        (!memberName.isPrivate() || getLibrary() == library)) {
+      return localMember;
+    }
+    return lookupSuperMemberInLibrary(memberName, library);
+  }
+
+  /**
    * Find the first member in the class chain with the given
    * [memberName]. This method is NOT to be used for resolving
    * unqualified sends because it does not implement the scoping