Adding smoothscroll polyfill for element.scroll* methods

.gitignore

@@ -24,3 +24,4 @@ polyfills/Element/prototype/inert/polyfill.js
 .nyc_output/
 polyfills/String/prototype/normalize/polyfill.js
 polyfills/AbortController/polyfill.js
+polyfills/smoothscroll/polyfill.js

package.json

@@ -47,8 +47,8 @@
     "@financial-times/polyfill-useragent-normaliser": "^1.2.0",
     "@iarna/toml": "^2.2.3",
     "@webcomponents/template": "^1.4.0",
-    "abort-controller": "^2.0.2",
     "Base64": "^1.0.0",
+    "abort-controller": "^2.0.2",
     "audio-context-polyfill": "^1.0.0",
     "diff": "1.4.0",
     "event-source-polyfill": "^0.0.9",
@@ -68,6 +68,7 @@
     "picturefill": "^3.0.1",
     "resize-observer-polyfill": "^1.5.1",
     "rimraf": "^2.6.2",
+    "smoothscroll-polyfill": "^0.4.4",
     "spdx-licenses": "^1.0.0",
     "stream-cache": "^0.0.2",
     "stream-from-promise": "^1.0.0",

polyfills/smoothscroll/config.toml

@@ -0,0 +1,24 @@
+dependencies = [
+  "requestAnimationFrame"
+]
+license = "MIT"
+spec = "https://drafts.csswg.org/cssom-view/#smooth-scrolling"
+repo = "https://github.com/webcomponents/polyfills/tree/master/packages/template"
+docs = "https://developer.mozilla.org/en/docs/Web/CSS/scroll-behavior"
+
+[browsers]
+edge = "* - 76"
+edge_mob = "*"
+ie = "*"
+ie_mob = "*"
+firefox = "4 - 36"
+opera = "*"
+safari = "*"
+chrome = "* - 60"
+ios_saf = "*"
+android = "*"
+
+[install]
+module = "smoothscroll-polyfill"
+paths = [ "dist/smoothscroll.min.js" ]
+

polyfills/smoothscroll/detect.js

@@ -0,0 +1 @@
+'scrollBehavior' in d.documentElement.style