Added for-loop variable tracking and regular closures/initializers captured variable tracking.

pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart

Index: pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart b/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
index 58be21caf77f6ab1642bea2fbfebff1930d50d9e..51a884ac3c3014daff1f85d4d2c0aee3d0ac43a8 100644
--- a/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_backend_strategy.dart
@@ -78,7 +78,7 @@ class KernelBackendStrategyImpl implements KernelBackendStrategy {
   @override
   ClosureConversionTask get closureDataLookup =>
       _closureDataLookup ??= new KernelClosureConversionTask(
-          _compiler.measurer, elementMap, _globalLocalsMap);
+          _compiler.measurer, elementMap, null, _globalLocalsMap);

[Emily Fortuna, 2017/06/30 17:58:40]

This seems... super sketchy. Johnni, I don't understand the distinction between
this strategy and the js_strategy? I mean, I understand conceptually, but is
this particular strategy actually being exercised anywhere? It just seemed less
implemented.

[Johnni Winther, 2017/07/03 07:36:57]

KernelBackendStrategy is to be replaced by JsStrategy

 
   @override
   WorkItemBuilder createCodegenWorkItemBuilder(ClosedWorld closedWorld) {