Sync core/timing/ interfaces with their specs, or lack thereof

Source/core/timing/DOMHighResTimeStamp.idl

Index: Source/core/timing/DOMHighResTimeStamp.idl
diff --git a/Source/modules/app_banner/BeforeInstallPromptEventInit.idl b/Source/core/timing/DOMHighResTimeStamp.idl
similarity index 63%
copy from Source/modules/app_banner/BeforeInstallPromptEventInit.idl
copy to Source/core/timing/DOMHighResTimeStamp.idl
index fc66cc8d9a905f64723a05065d055c7281fae321..e41c93a915a12e1b86a5c6377d75e60307ebc1d3 100644
--- a/Source/modules/app_banner/BeforeInstallPromptEventInit.idl
+++ b/Source/core/timing/DOMHighResTimeStamp.idl
@@ -2,6 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-dictionary BeforeInstallPromptEventInit : EventInit {
-    sequence<DOMString> platforms;
-};
+// https://w3c.github.io/hr-time/#sec-DOMHighResTimeStamp
+
+typedef double DOMHighResTimeStamp;