Revert "Change signature of lookupConstructor to only require a name."

pkg/compiler/lib/src/js_backend/backend.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.
 
 part of js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 const bool USE_CPS_IR = const bool.fromEnvironment("USE_CPS_IR");
 
@@ skipping 824 matching lines @@
         enqueue(enqueuer, getNativeInterceptorMethod, registry);
         enqueueClass(enqueuer, jsInterceptorClass, compiler.globalDependencies);
         enqueueClass(enqueuer, jsPlainJavaScriptObjectClass, registry);
       } else if (cls == mapLiteralClass) {
         // For map literals, the dependency between the implementation class
         // and [Map] is not visible, so we have to add it manually.
         Element getFactory(String name, int arity) {
           // The constructor is on the patch class, but dart2js unit tests don't
           // have a patch class.
           ClassElement implementation = cls.patch != null ? cls.patch : cls;
-          ConstructorElement ctor = implementation.lookupConstructor(name);
-          if (ctor == null
-              || (isPrivateName(name)
-                  && ctor.library != mapLiteralClass.library)) {
-            compiler.internalError(mapLiteralClass,
-                                   "Map literal class $mapLiteralClass missing "
-                                   "'$name' constructor"
-                                   "  ${mapLiteralClass.constructors}");
-          }
-          return ctor;
+          return implementation.lookupConstructor(
+            new Selector.callConstructor(
+                name, mapLiteralClass.library, arity),
+            (element) {
+              compiler.internalError(mapLiteralClass,
+                  "Map literal class $mapLiteralClass missing "
+                  "'$name' constructor"
+                  "  ${mapLiteralClass.constructors}");
+            });
         }
         mapLiteralConstructor = getFactory('_literal', 1);
         mapLiteralConstructorEmpty = getFactory('_empty', 0);
         enqueueInResolution(mapLiteralConstructor, registry);
         enqueueInResolution(mapLiteralConstructorEmpty, registry);
       }
     }
     if (cls == closureClass) {
       enqueue(enqueuer, findHelper('closureFromTearOff'), registry);
     }
@@ skipping 1661 matching lines @@
   }
 }
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final ConstantValue constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 }