Revert "Reduce use of getClosureInfoForMember and cleanup closure_test"

pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart

Index: pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
diff --git a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
index bda22d2add56cd5027966f9c57c3be6301433cd1..7f3458d79edb90b1dee5239f95575844aa711c3f 100644
--- a/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
+++ b/pkg/compiler/lib/src/ssa/kernel_ast_adapter.dart
@@ -133,8 +133,13 @@ class KernelAstAdapter extends KernelToElementMapBaseMixin
       target = kernel.functions[originTarget];
       // Closures require a lookup one level deeper in the closure class mapper.
       if (target == null) {
-        SynthesizedCallMethodElementX originTargetFunction = originTarget;
-        target = kernel.localFunctions[originTargetFunction.expression];
+        MethodElement originTargetFunction = originTarget;
+        ClosureRepresentationInfo classMap = _compiler
+            .backendStrategy.closureDataLookup
+            .getClosureInfoForMember(originTargetFunction);
+        if (classMap.closureEntity != null) {
+          target = kernel.localFunctions[classMap.closureEntity];
+        }
       }
     } else if (originTarget is FieldElement) {
       target = kernel.fields[originTarget];