Do not create placeholders for elements that won't be later renamed.

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 e4813c71903645dea9d6e8e612ea50e4205624be..87065c14a8d24c32809ce91d5d3cf1d5f009a26d 100644
--- a/lib/compiler/implementation/dart_backend/placeholder_collector.dart
+++ b/lib/compiler/implementation/dart_backend/placeholder_collector.dart
@@ -98,6 +98,9 @@ class PlaceholderCollector extends AbstractVisitor {
   Element currentElement;
   TreeElements treeElements;
 
+  LibraryElement get coreLibrary => compiler.coreLibrary;
+  FunctionElement get entryFunction => compiler.mainApp.find(Compiler.MAIN);
+
   PlaceholderCollector(this.compiler) :
       nullNodes = new Set<Node>(),
       unresolvedNodes = new Set<Identifier>(),
@@ -257,6 +260,8 @@ class PlaceholderCollector extends AbstractVisitor {
 
   void makeElementPlaceholder(Node node, Element element) {
     assert(element !== null);
+    if (element === entryFunction) return;

[Roman, 2012/08/21 07:44:58]

This is not the problem of your CL, but we should actually have an element for
MAIN, because otherwise another library may define it's own main element that
won't be renamed:

#library('lib.dart');
void main() {}

...
#import('lib.dart', prefix:'lib');
main() {
  lib.main();
}

To fix this, we should check MAIN element in rename and don't rename it, but
instead just add it to used top level identifiers. OR we can just add 'main' to
used top level identifiers in renamer at the beginning.

[Anton Muhin, 2012/08/21 09:16:54]

Good point, I'll fix it.

On 2012/08/21 07:44:58, Roman wrote:

+    if (element.getLibrary() === coreLibrary) return;
     elementNodes.putIfAbsent(element, () => new Set<Node>()).add(node);
   }