Update webvtt/, webxr/, and xhr/ from monorail results

See #798 for the methodology.

Author: stephenmcgruer

webvtt/rendering/cues-with-video/processing-model/META.yml

@@ -3,3 +3,7 @@ links:
       url: https://bugzilla.mozilla.org/show_bug.cgi?id=1463844
       results:
         - test: audio_has_no_subtitles.html
+    - product: chrome
+      url: https://crbug.com/1012242
+      results:
+        - test: basic.html

webvtt/rendering/cues-with-video/processing-model/selectors/cue_function/META.yml

@@ -0,0 +1,5 @@
+links:
+    - product: chrome
+      url: https://crbug.com/466072
+      results:
+        - test: id_color.html

webxr/dom-overlay/META.yml

@@ -0,0 +1,5 @@
+links:
+    - product: chrome
+      url: https://crbug.com/1101193
+      results:
+        - test: nested_fullscreen.https.html

xhr/META.yml

@@ -53,3 +53,7 @@ links:
       results:
         - test: response-json.htm
           status: FAIL
+    - product: chrome
+      url: https://crbug.com/881180
+      results:
+        - test: open-url-multi-window-4.htm