Update documentation of WindowPerformance and WorkerGlobalScopePerformance

Source/core/timing/WorkerGlobalScopePerformance.idl

Index: Source/core/timing/WorkerGlobalScopePerformance.idl
diff --git a/Source/core/timing/WorkerGlobalScopePerformance.idl b/Source/core/timing/WorkerGlobalScopePerformance.idl
index 1682a6e2a65ac98b767ca1bbafae622bd893d2fc..d283fd88c8e1b90b783f0b90138b8e86766620dc 100644
--- a/Source/core/timing/WorkerGlobalScopePerformance.idl
+++ b/Source/core/timing/WorkerGlobalScopePerformance.idl
@@ -28,9 +28,10 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-// TODO(philipj): There is no spec for WorkerGlobalScope.performance:
-// https://github.com/w3c/hr-time/issues/10
+// https://w3c.github.io/hr-time/#the-performance-interface
 
+// TODO(philipj): This should be a GlobalPerformance interface implemented by
+// Window and WorkerGlobalScope.
 partial interface WorkerGlobalScope {
     readonly attribute WorkerPerformance performance;
 };