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

Source/core/timing/PerformanceEntry.idl

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 11 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 // https://w3c.github.io/performance-timeline/#the-performanceentry-interface
+
 [
+    // TODO(philipj): Exposed=(Window,Worker)
     GarbageCollected,
 ] interface PerformanceEntry {
     readonly attribute DOMString name;
     readonly attribute DOMString entryType;
-    readonly attribute double startTime;
-    readonly attribute double duration;
-
+    readonly attribute DOMHighResTimeStamp startTime;
+    readonly attribute DOMHighResTimeStamp duration;
     serializer = {attribute};
 };