Extend flag enable-cssom-view-scroll-coordinates to M87

Bug: 721759
Change-Id: Ic2bfa6179e997c3db749ddba252bf720d587ce3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2359849Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: cathie chen <cathiechen@igalia.com>
Cr-Commit-Position: refs/heads/master@{#799040}

chrome/browser/flag-metadata.json

@@ -1352,7 +1352,7 @@
   {
     "name": "enable-cssom-view-scroll-coordinates",
     "owners": [ "cathiechen@igalia.com", "fwang@igalia.com" ],
-    "expiry_milestone": 85
+    "expiry_milestone": 87
   },
   {
     "name": "enable-custom-mac-paper-sizes",