Fix crashing bug for closures of the form () { return; }

pkg/dev_compiler/lib/src/compiler/code_generator.dart

 // Copyright (c) 2015, 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.
 
 import 'dart:collection' show HashMap, HashSet;
 import 'dart:math' show min, max;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 499 matching lines @@
 
       if (export is TypeDefiningElement ||
           export is FunctionElement ||
           _eagerTopLevelFields.contains(export)) {
         // classes, typedefs, functions, and eager init fields can be assigned
         // directly.
         // TODO(jmesserly): we don't know about eager init fields from other
         // modules we import, so we will never go down this code path for them.
         _moduleItems
             .add(js.statement('#.# = #;', [libraryName, name.selector, name]));
-      } else {
-        // top-level fields, getters, setters need to copy the property
-        // descriptor.
-        _moduleItems.add(_callHelperStatement(
-            'export(#, #, #);', [libraryName, name.receiver, name.selector]));
       }
     }
 
-    for (var export in exportedNames.definedNames.values) {
-      if (export is PropertyAccessorElement) {
-        export = (export as PropertyAccessorElement).variable;
-      }
+    // We only need to export main as it is the only method party of the
+    // publically exposed JS API for a library.
+    var export = exportedNames.get('main');
 
-      // Don't allow redefining names from this library.
-      if (currentNames.containsKey(export.name)) continue;
+    if (export == null) return;
+    if (export is PropertyAccessorElement) {
+      export = (export as PropertyAccessorElement).variable;
+    }
 
-      if (export.isSynthetic && export is PropertyInducingElement) {
-        _emitDeclaration(export.getter);
-        _emitDeclaration(export.setter);
-      } else {
-        _emitDeclaration(export);
-      }
-      if (export is ClassElement && export.typeParameters.isNotEmpty) {
-        // Export the generic name as well.
-        // TODO(jmesserly): revisit generic classes
-        emitExport(export, suffix: r'$');
-      }
-      emitExport(export);
+    // Don't allow redefining names from this library.
+    if (currentNames.containsKey(export.name)) return;
+
+    if (export.isSynthetic && export is PropertyInducingElement) {
+      _emitDeclaration(export.getter);
+      _emitDeclaration(export.setter);
+    } else {
+      _emitDeclaration(export);
     }
+    emitExport(export);
   }
 
   @override
   visitAsExpression(AsExpression node) {
     Expression fromExpr = node.expression;
     var from = getStaticType(fromExpr);
     var to = node.type.type;
 
     JS.Expression jsFrom = _visit(fromExpr);
     if (_inWhitelistCode(node)) return jsFrom;
@@ skipping 5037 matching lines @@
   var targetIdentifier = target as SimpleIdentifier;
 
   if (targetIdentifier.staticElement is! PrefixElement) return false;
   var prefix = targetIdentifier.staticElement as PrefixElement;
 
   // The library the prefix is referring to must come from a deferred import.
   var containingLibrary = (target.root as CompilationUnit).element.library;
   var imports = containingLibrary.getImportsWithPrefix(prefix);
   return imports.length == 1 && imports[0].isDeferred;
 }