Remove RequestIdleCallback runtime flag (status=stable)

third_party/WebKit/Source/core/dom/IdleDeadline.idl

Index: third_party/WebKit/Source/core/dom/IdleDeadline.idl
diff --git a/third_party/WebKit/Source/core/dom/IdleDeadline.idl b/third_party/WebKit/Source/core/dom/IdleDeadline.idl
index c06dffca6ed2c8abca94d9b9964130b7beff249f..2a5af6af31334b1f1944660fc4eb84696775020b 100644
--- a/third_party/WebKit/Source/core/dom/IdleDeadline.idl
+++ b/third_party/WebKit/Source/core/dom/IdleDeadline.idl
@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-[
-  RuntimeEnabled=RequestIdleCallback,
-] interface IdleDeadline {
+interface IdleDeadline {
     double timeRemaining();
     readonly attribute boolean didTimeout;
 };