Insert checks before deferred calls and accesses.

sdk/lib/_internal/compiler/implementation/js_backend/backend.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 js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 1047 matching lines @@
   void registerAbstractClassInstantiation(TreeElements elements) {
     enqueueInResolution(getThrowAbstractClassInstantiationError(), elements);
     // Also register the types of the arguments passed to this method.
     enqueueClass(compiler.enqueuer.resolution, compiler.stringClass, elements);
   }
 
   void registerFallThroughError(TreeElements elements) {
     enqueueInResolution(getFallThroughError(), elements);
   }
 
+  void registerCheckDeferredIsLoaded(TreeElements elements) {
+    enqueueInResolution(getCheckDeferredIsLoaded(), elements);
+    // Also register the types of the arguments passed to this method.
+    enqueueClass(compiler.enqueuer.resolution, compiler.stringClass, elements);
+  }
+
   void enableNoSuchMethod(Enqueuer world) {
     enqueue(world, getCreateInvocationMirror(), compiler.globalDependencies);
     world.registerInvocation(compiler.noSuchMethodSelector);
   }
 
   void registerSuperNoSuchMethod(TreeElements elements) {
     enqueueInResolution(getCreateInvocationMirror(), elements);
     enqueueInResolution(
         compiler.objectClass.lookupLocalMember(Compiler.NO_SUCH_METHOD),
         elements);
@@ skipping 441 matching lines @@
   }
 
   Element getAssertSubtype() {
     return compiler.findHelper('assertSubtype');
   }
 
   Element getCheckSubtypeOfRuntimeType() {
     return compiler.findHelper('checkSubtypeOfRuntimeType');
   }
 
+  Element getCheckDeferredIsLoaded() {
+    return compiler.findHelper('checkDeferredIsLoaded');
+  }
+
   Element getAssertSubtypeOfRuntimeType() {
     return compiler.findHelper('assertSubtypeOfRuntimeType');
   }
 
   Element getThrowNoSuchMethod() {
     return compiler.findHelper('throwNoSuchMethod');
   }
 
   Element getCreateRuntimeType() {
     return compiler.findHelper('createRuntimeType');
@@ skipping 366 matching lines @@
   }
 }
 
 /// Records that [constant] is used by [user.element].
 class Dependency {
   final Constant constant;
   final TreeElements user;
 
   const Dependency(this.constant, this.user);
 }