Reapply Issue 10911006.

lib/compiler/implementation/js_backend/emitter.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.
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
 class ClosureInvocationElement extends FunctionElement {
   ClosureInvocationElement(SourceString name,
@@ skipping 643 matching lines @@
     if (!checkedSetters.isEmpty()) {
       buffer.add(',\n');
       buffer.add('${Strings.join(checkedSetters, ",\n")}');
     }
     emitInstanceMembers(classElement, buffer, true);
     buffer.add('\n};\n\n');
   }
 
   void generateTypeTests(ClassElement cls,
                          void generateTypeTest(ClassElement element)) {
-    if (compiler.codegenWorld.isChecks.contains(cls)) {
+    if (compiler.codegenWorld.checkedClasses.contains(cls)) {
       generateTypeTest(cls);
     }
     generateInterfacesIsTests(cls, generateTypeTest, new Set<Element>());
   }
 
   void generateInterfacesIsTests(ClassElement cls,
                                  void generateTypeTest(ClassElement element),
                                  Set<Element> alreadyGenerated) {
     for (DartType interfaceType in cls.interfaces) {
       Element element = interfaceType.element;
       if (!alreadyGenerated.contains(element) &&
-          compiler.codegenWorld.isChecks.contains(element)) {
+          compiler.codegenWorld.checkedClasses.contains(element)) {
         alreadyGenerated.add(element);
         generateTypeTest(element);
       }
       generateInterfacesIsTests(element, generateTypeTest, alreadyGenerated);
     }
   }
 
   void emitClasses(CodeBuffer buffer) {
     Set<ClassElement> instantiatedClasses =
         compiler.codegenWorld.instantiatedClasses;
@@ skipping 610 matching lines @@
         sourceName = token.slowToString();
       }
       sourceMapBuilder.addMapping(
           sourceFile, token.charOffset, sourceName, offset);
     });
     return sourceMapBuilder.build(compiledFile);
   }
 }
 
 typedef void DefineMemberFunction(String invocationName, CodeBuffer definition);