Anton, maybe something worth doing? Shouldn't take long :)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/64282c8533da904acb78f1f9ef68c97619825b9c

commit 64282c8533da904acb78f1f9ef68c97619825b9c
Author: avayvod <avayvod@chromium.org>
Date: Tue May 09 17:24:42 2017

[RemotePlayback] Added IDL harness WebPlatform test for RemotePlayback API.

BUG= 666468 
TEST=run webkit tests locally

Review-Url: https://codereview.chromium.org/2862423002
Cr-Commit-Position: refs/heads/master@{#470366}

[modify] https://crrev.com/64282c8533da904acb78f1f9ef68c97619825b9c/third_party/WebKit/LayoutTests/W3CImportExpectations
[add] https://crrev.com/64282c8533da904acb78f1f9ef68c97619825b9c/third_party/WebKit/LayoutTests/external/wpt/interfaces/remoteplayback.idl
[add] https://crrev.com/64282c8533da904acb78f1f9ef68c97619825b9c/third_party/WebKit/LayoutTests/external/wpt/remote-playback/idlharness.html