Compute source spans for IR nodes and J/K-elements

pkg/compiler/lib/src/js_backend/element_strategy.dart

 // Copyright (c) 2017, 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.js_backend.element_strategy;
 
 import '../backend_strategy.dart';
 import '../closure.dart' show ClosureConversionTask, ClosureTask;
 import '../common.dart';
 import '../common/codegen.dart';
 import '../common/tasks.dart';
 import '../common/work.dart';
 import '../compiler.dart';
 import '../elements/elements.dart';
 import '../enqueue.dart';
 import '../io/multi_information.dart' show MultiSourceInformationStrategy;
 import '../io/position_information.dart' show PositionSourceInformationStrategy;
 import '../io/source_information.dart';
 import '../io/start_end_information.dart'
     show StartEndSourceInformationStrategy;
 import '../js/js_source_mapping.dart' show JavaScriptSourceInformationStrategy;
 import '../js_backend/backend.dart';
 import '../js_backend/native_data.dart';
 import '../js_emitter/sorter.dart';
+import '../resolution/resolution_strategy.dart';
 import '../ssa/builder.dart';
 import '../ssa/rasta_ssa_builder_task.dart';
 import '../ssa/ssa.dart';
 import '../options.dart';
 import '../universe/world_builder.dart';
 import '../universe/world_impact.dart';
 import '../world.dart';
 
 /// Strategy for using the [Element] model from the resolver as the backend
 /// model.
-class ElementBackendStrategy implements BackendStrategy {
+class ElementBackendStrategy extends ComputeSpannableMixin
+    implements BackendStrategy {
   final Compiler _compiler;
   final ClosureConversionTask closureDataLookup;
   SourceInformationStrategy _sourceInformationStrategy;
 
   ElementBackendStrategy(this._compiler)
       : closureDataLookup = new ClosureTask(_compiler);
 
   ClosedWorldRefiner createClosedWorldRefiner(
           covariant ClosedWorldImpl closedWorld) =>
       closedWorld;
@@ skipping 112 matching lines @@
 
   MemberElement get element => resolvedAst.element;
 
   WorldImpact run() {
     registry = new CodegenRegistry(_closedWorld.elementEnvironment, element);
     return _backend.codegen(this, _closedWorld);
   }
 
   String toString() => 'CodegenWorkItem(${resolvedAst.element})';
 }