Use DOMHighResTimeStamp in VideoPlaybackQuality and MIDIOutput

VideoPlaybackQuality.idl and MIDIOutput.idl uses double as the time type.
However, the specs are updated at some point to usp DOMHighResTimeStamp.

https://wicg.github.io/media-playback-quality/#idl-def-videoplaybackquality
https://webaudio.github.io/web-midi-api/#MIDIOutput

Change-Id: Ib9d7e9a5c066ab673c880cbda3d22817fcff961d
Reviewed-on: https://chromium-review.googlesource.com/892841Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532824}

third_party/WebKit/Source/modules/mediasource/VideoPlaybackQuality.idl

@@ -30,7 +30,7 @@
 [
     RuntimeEnabled=MediaSourceExperimental
 ] interface VideoPlaybackQuality {
-    readonly attribute double creationTime;
+    readonly attribute DOMHighResTimeStamp creationTime;
     readonly attribute unsigned long totalVideoFrames;
     readonly attribute unsigned long droppedVideoFrames;
     readonly attribute unsigned long corruptedVideoFrames;

third_party/WebKit/Source/modules/webmidi/MIDIOutput.idl

@@ -32,6 +32,6 @@
 
 interface MIDIOutput : MIDIPort {
     // TODO(toyoshim): implement void clear()
-    [RaisesException] void send(Uint8Array data, optional double timestamp);
-    [RaisesException] void send(sequence<unsigned long> data, optional double timestamp);
+    [RaisesException] void send(Uint8Array data, optional DOMHighResTimeStamp timestamp);
+    [RaisesException] void send(sequence<unsigned long> data, optional DOMHighResTimeStamp timestamp);
 };