Compute KernelClosureRepresentationInfo.variableIsUsedInTryOrSync

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

Index: pkg/compiler/lib/src/js_backend/element_strategy.dart
diff --git a/pkg/compiler/lib/src/js_backend/element_strategy.dart b/pkg/compiler/lib/src/js_backend/element_strategy.dart
index 9ab811484f4c5ebb9a1aef0f579baceedb2fb83e..7d2bc46b8dc7bde5161d6c9b31e1a629675c28e4 100644
--- a/pkg/compiler/lib/src/js_backend/element_strategy.dart
+++ b/pkg/compiler/lib/src/js_backend/element_strategy.dart
@@ -34,9 +34,11 @@ import '../world.dart';
 /// model.
 class ElementBackendStrategy implements BackendStrategy {
   final Compiler _compiler;
+  final ClosureConversionTask closureDataLookup;
   SourceInformationStrategy _sourceInformationStrategy;
 
-  ElementBackendStrategy(this._compiler);
+  ElementBackendStrategy(this._compiler)
+      : closureDataLookup = new ClosureTask(_compiler);
 
   ClosedWorldRefiner createClosedWorldRefiner(ClosedWorldImpl closedWorld) =>
       closedWorld;
@@ -44,10 +46,6 @@ class ElementBackendStrategy implements BackendStrategy {
   Sorter get sorter => const ElementSorter();
 
   @override
-  ClosureConversionTask createClosureConversionTask(Compiler compiler) =>

[Emily Fortuna, 2017/06/19 17:44:41]

is taking this out the direction you want to go? I went the other way because I
thought I'd match the SsaBuilderTask, but then after Siggi pointed out you were
going the other direction:
https://codereview.chromium.org/2937203002/diff/40001/pkg/compiler/lib/src/ke...

I'm fine doing it this way -- I was just trying to be consistent! :-P

[Johnni Winther, 2017/06/20 10:33:12]

I want to get rid of CompilerTask as base classes. It is just a stop-watch and
should be passed to the actual task.

-      new ClosureTask(compiler);
-
-  @override
   CodegenWorldBuilder createCodegenWorldBuilder(
       NativeBasicData nativeBasicData,
       ClosedWorld closedWorld,