Re-land r13557 on behalf of Alexander.

lib/compiler/implementation/elements/elements.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #library('elements');
 
 #import('dart:uri');
 
 // TODO(ahe): Rename prefix to 'api' when VM bug is fixed.
 #import('../../compiler.dart', prefix: 'api_e');
@@ skipping 1457 matching lines @@
     }
     SourceString fieldName = fieldMember.name;
     while (true) {
       Element foundMember = lookupClass.lookupMember(fieldName);
       if (foundMember == fieldMember) return false;
       if (foundMember.isField()) return true;
       lookupClass = foundMember.getEnclosingClass().superclass;
     }
   }
 
-  Element lookupConstructor(SourceString className,
-                            [SourceString constructorName =
-                                 const SourceString(''),
-                            Element noMatch(Element)]) {
-    // TODO(karlklose): have a map from class names to a map of constructors
-    //                  instead of creating the name here?
+  Element validateConstructorLookupResults(Selector selector,
+                                           Element result,
+                                           Element noMatch(Element)) {
+    if (result === null
+        || !result.isConstructor()
+        || (selector.name.isPrivate()
+            && result.getLibrary() != selector.library)) {
+      result = noMatch !== null ? noMatch(result) : null;
+    }
+    return result;
+  }
+
+  // TODO(aprelev@gmail.com): Peter believes that it would be great to
+  // make noMatch a required argument. Peter's suspicion is that most
+  // callers of this method would benefit from using the noMatch method.
+  Element lookupConstructor(Selector selector, [Element noMatch(Element)]) {
     SourceString normalizedName;
-    if (constructorName !== const SourceString('')) {
+    SourceString className = this.name;
+    SourceString constructorName = selector.name;
+    if (constructorName !== const SourceString('') &&
+        ((className === null) ||
+         (constructorName.slowToString() != className.slowToString()))) {
       normalizedName = Elements.constructConstructorName(className,
                                                          constructorName);
     } else {
       normalizedName = className;
     }
     Element result = localLookup(normalizedName);
-    if (result === null || !result.isConstructor()) {
-      result = noMatch !== null ? noMatch(result) : null;
-    }
-    return result;
+    return validateConstructorLookupResults(selector, result, noMatch);
+  }
+
+  Element lookupFactoryConstructor(Selector selector,
+                                   [Element noMatch(Element)]) {
+    SourceString constructorName = selector.name;
+    Element result = localLookup(constructorName);
+    return validateConstructorLookupResults(selector, result, noMatch);
   }
 
   bool get hasConstructor {
     // Search in scope to be sure we search patched constructors.
     for (var element in localScope.getValues()) {
       if (element.isConstructor()) return true;
     }
     return false;
   }
 
@@ skipping 439 matching lines @@
 
   MetadataAnnotation ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveMetadataAnnotation(this);
     }
     return this;
   }
 
   String toString() => 'MetadataAnnotation($value, $resolutionState)';
 }