Fix dart2js async error handling of finallies nested in finallies.

pkg/compiler/lib/src/js/rewrite_async.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.
 
 library rewrite_async;
 
 import "dart:math" show max;
 import 'dart:collection';
 
 import 'package:_internal/compiler/js_lib/shared/async_await_error_codes.dart'
@@ skipping 641 matching lines @@
     rewrittenBody = js.js.statement('while (true) {#}', rewrittenBody);
     List<js.VariableInitialization> variables =
         new List<js.VariableInitialization>();
 
     variables.add(_makeVariableInitializer(goto, js.number(0)));
     variables.addAll(variableInitializations());
     variables.add(
         _makeVariableInitializer(handler, js.number(rethrowLabel)));
     variables.add(_makeVariableInitializer(currentError, null));
     if (analysis.hasFinally || (isAsyncStar && analysis.hasYield)) {
-      variables.add(_makeVariableInitializer(next, null));
+      variables.add(_makeVariableInitializer(next,
+          new js.ArrayInitializer(<js.Expression>[])));
     }
     if (analysis.hasThis && !isSyncStar) {
       // Sync* functions must remember `this` on the level of the outer
       // function.
       variables.add(_makeVariableInitializer(self, js.js('this')));
     }
     variables.addAll(localVariables.map(
         (js.VariableDeclaration declaration) {
       return new js.VariableInitialization(declaration, null);
     }));
@@ skipping 736 matching lines @@
 
     js.Node last = jumpTargets.removeLast();
     assert(last == node);
 
     if (node.finallyPart == null) {
       setErrorHandler();
       addGoto(afterFinallyLabel);
     } else {
       // The handler is reset as the first thing in the finally block.
       addStatement(
-          js.js.statement("# = [#];", [next, js.number(afterFinallyLabel)]));
+          js.js.statement("#.push(#);", [next, js.number(afterFinallyLabel)]));
       addGoto(finallyLabel);
     }
 
     if (node.catchPart != null) {
       beginLabel(handlerLabel);
       // [uncaughtLabel] is the handler for the code in the catch-part.
       // It ensures that [nextName] is set up to run the right finally blocks.
       handlerLabels[node.catchPart] = uncaughtLabel;
       jumpTargets.add(node.catchPart);
       setErrorHandler();
       // The catch declaration name can shadow outer variables, so a fresh name
       // is needed to avoid collisions.  See Ecma 262, 3rd edition,
       // section 12.14.
       String errorRename = freshName(node.catchPart.declaration.name);
       localVariables.add(new js.VariableDeclaration(errorRename));
       variableRenamings
           .add(new Pair(node.catchPart.declaration.name, errorRename));
       addStatement(js.js.statement("# = #;", [errorRename, currentError]));
       visitStatement(node.catchPart.body);
       variableRenamings.removeLast();
       if (node.finallyPart != null) {
         // The error has been caught, so after the finally, continue after the
         // try.
-        addStatement(js.js.statement("# = [#];",
-                                     [next, js.number(afterFinallyLabel)]));
+        addStatement(
+            js.js.statement("#.push(#);",
+                            [next, js.number(afterFinallyLabel)]));
         addGoto(finallyLabel);
       } else {
         addGoto(afterFinallyLabel);
       }
       js.Node last = jumpTargets.removeLast();
       assert(last == node.catchPart);
     }
 
     // The "uncaught"-handler tells the finally-block to continue with
     // the enclosing finally-blocks until the current catch-handler.
@@ skipping 1019 matching lines @@
     return condition || body;
   }
 
   @override
   bool visitDartYield(js.DartYield node) {
     hasYield = true;
     visit(node.expression);
     return true;
   }
 }