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

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 4bed08dbcd52e3cd2dae94dc80666b8befea235a..d9f00ebba25b598571cdfeeb194e3fb37c3caa21 100644
--- a/lib/compiler/implementation/elements/elements.dart
+++ b/lib/compiler/implementation/elements/elements.dart
@@ -1374,21 +1374,17 @@ class ClassElement extends ScopeContainerElement
     }
   }
 
-  Element lookupConstructor(SourceString className,
-                            [SourceString constructorName =
-                                 const SourceString(''),
-                            Element noMatch(Element)]) {
+  Element lookupConstructor(Selector selector, [Element noMatch(Element)]) {
     // TODO(karlklose): have a map from class names to a map of constructors
     //                  instead of creating the name here?
-    SourceString normalizedName;
-    if (constructorName !== const SourceString('')) {
-      normalizedName = Elements.constructConstructorName(className,
-                                                         constructorName);
-    } else {
-      normalizedName = className;
-    }
+    SourceString normalizedName =
+        Elements.constructConstructorNameFromOneName(selector.name);
+
     Element result = localLookup(normalizedName);
-    if (result === null || !result.isConstructor()) {
+
+    if (result === null
+        || !result.isConstructor()
+        || (selector.isPrivate() && result.getLibrary() != selector.library)) {
       result = noMatch !== null ? noMatch(result) : null;
     }
     return result;
@@ -1595,6 +1591,18 @@ class Elements {
     return new SourceString('$r\$$s');
   }
 
+  static SourceString constructConstructorNameFromOneName(SourceString name) {

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

Somehow it would be simpler if the name stored in the selector was the
normalized one. Where do we need it to contain the dot?

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

I'm uncomfortable about adding this method. The method above,
"constructConstructorName", should be sufficient (but is a hack).

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

Okay, got rid of the method and storing normalized name in Selector now.
Dotted names are needed for diagnostic only, it seems.

+    var strName = name.slowToString();

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

Try to avoid abbreviations. I'd go for dotIndex and nameString in this case.

+    var ndxDot = strName.indexOf(".");
+    if (ndxDot >= 0) {
+      return new SourceString(
+          '${strName.substring(0, ndxDot)}\$'
+          '${strName.substring(ndxDot + 1, strName.length)}');
+    } else {
+      return name;
+    }
+  }
+
   static const SourceString OPERATOR_EQUALS =
       const SourceString(@'operator$eq');