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

sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.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 dart2js.js_emitter;
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
  * in classes) are ignored, since they can be treated as non-class elements.
  *
@@ skipping 941 matching lines @@
                        js('init.dispatchPropertyName = property')))])])());
   }
 
   String generateDispatchPropertyName(int seed) {
     // TODO(sra): MD5 of contributing source code or URIs?
     return '___dart_dispatch_record_ZxYxX_${seed}_';
   }
 
   emitMain(CodeBuffer buffer) {
     if (compiler.isMockCompilation) return;
-    Element main = compiler.mainApp.find(Compiler.MAIN);
+    Element main = compiler.mainFunction;
     String mainCall = null;
     if (compiler.hasIsolateSupport()) {
       Element isolateMain =
         compiler.isolateHelperLibrary.find(Compiler.START_ROOT_ISOLATE);
       mainCall = buildIsolateSetup(buffer, main, isolateMain);
     } else {
       mainCall = '${namer.isolateAccess(main)}()';
     }
     if (backend.needToInitializeDispatchProperty) {
       buffer.write(
@@ skipping 619 matching lines @@
   }
 
   bool isDeferred(Element element) {
     return compiler.deferredLoadTask.isDeferred(element);
   }
 
   bool get areAnyElementsDeferred {
     return compiler.deferredLoadTask.areAnyElementsDeferred;
   }
 }