Enable CSSOMViewScrollCoordinates flag by default

Enables the feature be default on ToT and on M86+.
Blink API Owners approval of this launch: https://groups.google.com/a/chromium.org/d/msg/blink-dev/7X2CKPGeEa0/L2itpO2bAgAJ

We will be using a finch experiment to enable the
flag on M85+ that will give us the ability to pull
back if needed.

Bug: 721759
Change-Id: I61259b0fbaabbdbfc93b9423afae56165b1e30bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2310799
Auto-Submit: Majid Valipour <majidvp@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790711}

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -506,7 +506,7 @@
     },
     {
       name: "CSSOMViewScrollCoordinates",
-      status: "experimental",
+      status: "stable",
     },
     {
       name: "CSSPaintAPIArguments",