Add ConstructorBodyEntity

pkg/compiler/lib/src/js_model/closure.dart

Index: pkg/compiler/lib/src/js_model/closure.dart
diff --git a/pkg/compiler/lib/src/js_model/closure.dart b/pkg/compiler/lib/src/js_model/closure.dart
index 7202e5ce7e733a36b12efa70d8e26e8b12da4c4e..042568b095d6f19a21f2f4f1b036c8ae0b9c42cc 100644
--- a/pkg/compiler/lib/src/js_model/closure.dart
+++ b/pkg/compiler/lib/src/js_model/closure.dart
@@ -145,8 +145,17 @@ class KernelClosureConversionTask extends ClosureConversionTask<ir.Node> {
   @override
   // TODO(efortuna): Eventually closureRepresentationMap[node] should always be
   // non-null, and we should just test that with an assert.
-  ClosureRepresentationInfo getClosureRepresentationInfo(Entity entity) =>
-      _closureRepresentationMap[entity] ?? const ClosureRepresentationInfo();
+  ClosureRepresentationInfo getClosureRepresentationInfo(Entity entity) {
+    // TODO(johnniwinther): Remove this check when constructor bodies a created
+    // eagerly with the J-model; a constructor body should have it's own
+    // [ClosureRepresentationInfo].
+    if (entity is ConstructorBodyEntity) {
+      ConstructorBodyEntity constructorBody = entity;
+      entity = constructorBody.constructor;
+    }
+    return _closureRepresentationMap[entity] ??
+        const ClosureRepresentationInfo();
+  }
 }
 
 class KernelScopeInfo extends ScopeInfo {