Add FunctionEntity.asyncMarker and refactor SourceInformationStrategy to avoid ResolvedAst

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 '../common.dart';
 import '../common/codegen.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 '../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 {
   final Compiler _compiler;
+  SourceInformationStrategy _sourceInformationStrategy;
 
   ElementBackendStrategy(this._compiler);
 
   ClosedWorldRefiner createClosedWorldRefiner(ClosedWorldImpl closedWorld) =>
       closedWorld;
 
   Sorter get sorter => const ElementSorter();
 
   void convertClosures(ClosedWorldRefiner closedWorldRefiner) {
     _compiler.closureToClassMapper.createClosureClasses(closedWorldRefiner);
@@ skipping 18 matching lines @@
         _compiler.backend, closedWorld, _compiler.options);
   }
 
   @override
   SsaBuilderTask createSsaBuilderTask(JavaScriptBackend backend,
       SourceInformationStrategy sourceInformationStrategy) {
     return _compiler.options.useKernel
         ? new RastaSsaBuilderTask(backend, sourceInformationStrategy)
         : new SsaAstBuilderTask(backend, sourceInformationStrategy);
   }
+
+  SourceInformationStrategy get sourceInformationStrategy {
+    return _sourceInformationStrategy ??= createSourceInformationStrategy(
+        generateSourceMap: _compiler.options.generateSourceMap,
+        useMultiSourceInfo: _compiler.options.useMultiSourceInfo,
+        useNewSourceInfo: _compiler.options.useNewSourceInfo);
+  }
+
+  static SourceInformationStrategy createSourceInformationStrategy(
+      {bool generateSourceMap: false,
+      bool useMultiSourceInfo: false,
+      bool useNewSourceInfo: false}) {
+    if (!generateSourceMap) return const JavaScriptSourceInformationStrategy();
+    if (useMultiSourceInfo) {
+      if (useNewSourceInfo) {
+        return const MultiSourceInformationStrategy(const [
+          const PositionSourceInformationStrategy(),
+          const StartEndSourceInformationStrategy()
+        ]);
+      } else {
+        return const MultiSourceInformationStrategy(const [
+          const StartEndSourceInformationStrategy(),
+          const PositionSourceInformationStrategy()
+        ]);
+      }
+    } else if (useNewSourceInfo) {
+      return const PositionSourceInformationStrategy();
+    } else {
+      return const StartEndSourceInformationStrategy();
+    }
+  }
 }
 
 /// Builder that creates the work item necessary for the code generation of a
 /// [MemberElement].
 class ElementCodegenWorkItemBuilder extends WorkItemBuilder {
   final JavaScriptBackend _backend;
   final ClosedWorld _closedWorld;
   final CompilerOptions _options;
 
   ElementCodegenWorkItemBuilder(
@@ skipping 42 matching lines @@
 
   MemberElement get element => resolvedAst.element;
 
   WorldImpact run() {
     registry = new CodegenRegistry(element);
     return _backend.codegen(this, _closedWorld);
   }
 
   String toString() => 'CodegenWorkItem(${resolvedAst.element})';
 }