Remove unnecessary casts.

pkg/kernel/lib/transformations/closure/converter.dart

 // Copyright (c) 2016, 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 kernel.transformations.closure.converter;
 
 import '../../ast.dart'
     show
         Arguments,
         Block,
@@ skipping 658 matching lines @@
       Field self = new Field(new Name("self"), fileUri: currentFileUri);
       self.type = substitute(procedure.enclosingClass.thisType, substitution);
       fields = <Field>[self];
       receiver = new PropertyGet(new ThisExpression(), self.name, self);
     }
 
     // Find the closure class for the function. If there isn't one, create it.
     String closureClassName = createNameForClosureClass(procedure.function);
     Class closureClass = null;
     for (TreeNode node in newLibraryMembers) {
-      if (node is Class && (node as Class).name == closureClassName) {
-        closureClass = node as Class;
+      if (node is Class && node.name == closureClassName) {

[ahe, 2017/03/16 09:37:09]

Because of the test "node is Class", the compiler now knows that node has the
type Class. As long as you don't assign to node in the code that's guarded by
this test (or in a closure anywhere), there's no need for a cast.

[Dmitry Stefantsov, 2017/03/16 09:42:10]

Thanks!

+        closureClass = node;
       }
     }
     if (closureClass == null) {
       closureClass = createClosureClass(procedure.function,
           fields: fields, substitution: substitution);
       closureClass.addMember(new Procedure(
           new Name("call"),
           ProcedureKind.Method,
           forwardFunction(procedure, receiver, substitution),
           fileUri: currentFileUri));
@@ skipping 142 matching lines @@
   // TODO(ahe): Remove this method when we don't generate closure classes
   // anymore.
   void addClosureClassNote(Class closureClass) {
     closureClass.addMember(new Field(new Name("note"),
         type: coreTypes.stringClass.rawType,
         initializer: new StringLiteral(
             "This is temporary. The VM doesn't need closure classes."),
         fileUri: currentFileUri));
   }
 }