Do not suppress implicit constructors that need a super call.

lib/runtime/dart/_js_helper.js

Index: lib/runtime/dart/_js_helper.js
diff --git a/lib/runtime/dart/_js_helper.js b/lib/runtime/dart/_js_helper.js
index be3814a2864546a7b5e54b0ec1bdb4594889f56f..e43d8f434605e86a18e93d87fbba5c037807e73b 100644
--- a/lib/runtime/dart/_js_helper.js
+++ b/lib/runtime/dart/_js_helper.js
@@ -2883,7 +2883,11 @@ var _js_helper;
   function closureFromTearOff(receiver, functions, reflectionInfo, isStatic, jsArguments, name) {
     return Closure.fromTearOff(receiver, _interceptors.JSArray.markFixedList(dart.as(functions, core.List)), _interceptors.JSArray.markFixedList(dart.as(reflectionInfo, core.List)), !!isStatic, jsArguments, name);
   }
-  class TearOffClosure extends Closure {}
+  class TearOffClosure extends Closure {
+    TearOffClosure() {
+      super.Closure();
+    }
+  }
   let _self = Symbol('_self');
   let _target = Symbol('_target');
   let _name = Symbol('_name');