No longer store the compilation-context in WorkItem.

pkg/compiler/lib/src/common/backend_api.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.
 
 library dart2js.backend_api;
 
 import 'dart:async' show Future;
 
 import '../common.dart';
 import '../common/codegen.dart' show CodegenImpact;
@@ skipping 16 matching lines @@
 import '../native/native.dart' as native show NativeEnqueuer, maybeEnableNative;
 import '../patch_parser.dart'
     show checkNativeAnnotation, checkJsInteropAnnotation;
 import '../serialization/serialization.dart'
     show DeserializerPlugin, SerializerPlugin;
 import '../tree/tree.dart' show Node;
 import '../universe/world_impact.dart' show ImpactStrategy, WorldImpact;
 import 'codegen.dart' show CodegenWorkItem;
 import 'registry.dart' show Registry;
 import 'tasks.dart' show CompilerTask;
-import 'work.dart' show ItemCompilationContext;
 
 abstract class Backend extends Target {
   final Compiler compiler;
 
   Backend(this.compiler);
 
   /// Returns true if the backend supports reflection.
   bool get supportsReflection;
 
   /// The [ConstantSystem] used to interpret compile-time constants for this
@@ skipping 50 matching lines @@
   }
 
   /// Generates the output and returns the total size of the generated code.
   int assembleProgram();
 
   List<CompilerTask> get tasks;
 
   void onResolutionComplete() {}
   void onTypeInferenceComplete() {}
 
-  ItemCompilationContext createItemCompilationContext() {
-    return new ItemCompilationContext();
-  }
-
   bool classNeedsRti(ClassElement cls);
   bool methodNeedsRti(FunctionElement function);
 
   /// Enable compilation of code with compile time errors. Returns `true` if
   /// supported by the backend.
   bool enableCodegenWithErrorsIfSupported(Spannable node);
 
   /// Enable deferred loading. Returns `true` if the backend supports deferred
   /// loading.
   bool enableDeferredLoadingIfSupported(Spannable node, Registry registry);
@@ skipping 287 matching lines @@
   }
 }
 
 /// Interface for serialization of backend specific data.
 class BackendSerialization {
   const BackendSerialization();
 
   SerializerPlugin get serializer => const SerializerPlugin();
   DeserializerPlugin get deserializer => const DeserializerPlugin();
 }