Set owner and expiration for experimental web platform features

Set owner as blink core owners with no expiry.

Change-Id: I007688bfa75db013745032454a159a1fc306cf65
Reviewed-on: https://chromium-review.googlesource.com/c/1460868Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#630349}

chrome/browser/flag-metadata.json

@@ -1170,8 +1170,10 @@
   },
   {
     "name": "enable-experimental-web-platform-features",
-    // "owners": [ "your-team" ],
-    "expiry_milestone": 76
+    "owners": [ "//third_party/blink/renderer/core/OWNERS" ],
+    // Used by developers to activate experimental features in blink.
+    // See //third_party/blink/renderer/platform/runtime_enabled_features.json5.
+    "expiry_milestone": -1
   },
   {
     "name": "enable-first-run-ui-transitions",