Made dart2js constructor lookup logic "private"-aware, fixed 4740 bug.

lib/compiler/implementation/dart_backend/placeholder_collector.dart

Index: lib/compiler/implementation/dart_backend/placeholder_collector.dart
diff --git a/lib/compiler/implementation/dart_backend/placeholder_collector.dart b/lib/compiler/implementation/dart_backend/placeholder_collector.dart
index 91dea96eccfcd4842326578a43b5dfa2282b0880..d00b8c4f28ef5d05427b4ce108647998a5ab495c 100644
--- a/lib/compiler/implementation/dart_backend/placeholder_collector.dart
+++ b/lib/compiler/implementation/dart_backend/placeholder_collector.dart
@@ -446,7 +446,9 @@ class PlaceholderCollector extends AbstractVisitor {
             if (element is TypedefElement) return true;
             ClassElement classElement = element;
             final constructor = classElement.lookupConstructor(
-                receiver.source, selector.source);
+              new Selector.callConstructor(receiver.source, // class name

[kasperl, 2012/09/24 05:52:38]

Maybe add two local variables (className and constructorName) to avoid having to
add these end-of-line comments?

4 space indent.

[ahe, 2012/09/24 06:43:31]

This code does not belong in the dart_backend to begin with. I don't think we
should modify this code or try to get it to work. The dart backend should not do
resolution, or attempt to implement features that we have not yet implemented in
the front-end.

If this code breaks, so be it. I do not want to waste time on two resolvers.

[aam-me, 2012/09/25 04:15:18]

Okay, I removed this file from the changelist.

+                                           selector.source, // constructor name
+                                           currentElement.getLibrary()));
             return constructor === null;
           }
           if (!hasPrefix()) target = send.receiver;