Use failedAt in more places

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

Index: pkg/compiler/lib/src/js_backend/impact_transformer.dart
diff --git a/pkg/compiler/lib/src/js_backend/impact_transformer.dart b/pkg/compiler/lib/src/js_backend/impact_transformer.dart
index 6703c9fe3c8ac55797ae3664d32edb0ec96abfcd..94d4190b5a026b9344cc2fb1de174698fc76e7b6 100644
--- a/pkg/compiler/lib/src/js_backend/impact_transformer.dart
+++ b/pkg/compiler/lib/src/js_backend/impact_transformer.dart
@@ -263,8 +263,10 @@ class JavaScriptImpactTransformer extends ImpactTransformer {
           registerImpact(_impacts.stringLiteral);
           break;
         default:
-          assert(invariant(NO_LOCATION_SPANNABLE, false,
-              message: "Unexpected constant literal: ${constant.kind}."));
+          assert(
+              false,
+              failedAt(NO_LOCATION_SPANNABLE,
+                  "Unexpected constant literal: ${constant.kind}."));
       }
     }