Re-land "Search for main in the exported names of the main library, not in the library itself."

sdk/lib/_internal/compiler/implementation/elements/modelx.dart

 // Copyright (c) 2013, 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.modelx;
 
 import 'elements.dart';
 import '../../compiler.dart' as api;
 import '../tree/tree.dart';
 import '../util/util.dart';
@@ skipping 884 matching lines @@
   /** Look up a top-level element in this library, but only look for
     * non-imported elements. Returns null if no such element exist. */
   Element findLocal(String elementName) {
     // TODO(johnniwinther): How to handle injected elements in the patch
     // library?
     Element result = localScope.lookup(elementName);
     if (result == null || result.getLibrary() != this) return null;
     return result;
   }
 
+  Element findExported(String elementName) {
+    for (Link link = exports; !link.isEmpty; link = link.tail) {
+      Element element = link.head;
+      if (element.name == elementName) return element;
+    }
+    return null;
+  }
+
   void forEachExport(f(Element element)) {
     exports.forEach((Element e) => f(e));
   }
 
   void forEachLocalMember(f(Element element)) {
     if (isPatch) {
       // Patch libraries traverse both origin and injected members.
       origin.localMembers.forEach(f);
 
       void filterPatch(Element element) {
@@ skipping 1448 matching lines @@
 
   MetadataAnnotation ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveMetadataAnnotation(this);
     }
     return this;
   }
 
   String toString() => 'MetadataAnnotation($value, $resolutionState)';
 }