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

third_party/WebKit/LayoutTests/W3CImportExpectations

 # This file controls which subdirectories of the w3c test repos we import.
 #
 # This file acts as a blacklist; directories and files not listed here will
 # automatically be found and imported.
 #
 # This file is read by webkitpy/w3c/directory_owners_extractor.py to decide who
 # to contact for new failures; it will read entries with the following format:
 # When removing blacklist entries:
 # * Comment out the line rather than deleting it, to show it is intentional.
 # * Change [ Skip ] to [ Pass ]
@@ skipping 273 matching lines @@
 external/wpt/html-longdesc [ Skip ]
 ## Owners: rijubrata.bhaumik@intel.com,mcasas@chromium.org
 # external/wpt/html-media-capture [ Pass ]
 ## Owners: loading-dev@chromium.org
 # external/wpt/http [ Pass ]
 ## Owners: none; No tests in the directory.
 # external/wpt/images [ Pass ]
 external/wpt/imagebitmap-renderingcontext [ Skip ]
 ## Owners: smcgruer@chromium.org
 # external/wpt/infrastructure [ Pass ]
+## Owners: none; No tests in the directory.
+# external/wpt/interfaces [ Pass ]
 ## Owners: dom-dev@chromium.org
 # external/wpt/innerText [ Pass ]
 external/wpt/js [ Skip ]
 external/wpt/lint [ Skip ]
 external/wpt/manifest [ Skip ]
 external/wpt/mathml [ Skip ]
 ## Owners: none; No tests in the directory.
 # external/wpt/media [ Pass ]
 ## Owners: mlamouri@chromium.org,zqzhang@chromium.org
 # external/wpt/mediasession [ Pass ]
@@ skipping 442 matching lines @@
 external/wpt/uievents/order-of-events/mouse-events/click-on-html-manual.html [ Skip ]
 external/wpt/uievents/order-of-events/mouse-events/click-order-manual.html [ Skip ]
 external/wpt/uievents/order-of-events/mouse-events/mouseevents-mousemove-manual.htm [ Skip ]
 external/wpt/uievents/order-of-events/mouse-events/mousemove-across-manual.html [ Skip ]
 external/wpt/uievents/order-of-events/mouse-events/mousemove-between-manual.html [ Skip ]
 external/wpt/keyboard-lock/idlharness.https.html [ Skip ]
 external/wpt/keyboard-lock/navigator-cancelKeyboardLock.https.html [ Skip ]
 external/wpt/keyboard-lock/navigator-requestKeyboardLock.https.html [ Skip ]
 external/wpt/keyboard-lock/navigator-requestKeyboardLock-two-parallel-requests.https.html [ Skip ]
 external/wpt/keyboard-lock/navigator-requestKeyboardLock-two-sequential-requests.https.html [ Skip ]