Repository: Modernizr/Modernizr (js)

Issue:
Add support for ResizeObserver
As far as I know this feature-detect does not exist. I'll be happy to create a PR for this if needed.

Pull request description:
Add support for ResizeObserver
Adds a simple test testing ResizeObserver existence on window.

Fixes #2581 

Patch:
diff --git a/feature-detects/window/resizeobserver.js b/feature-detects/window/resizeobserver.js
new file mode 100644
index 00000000..c95e2b63
--- /dev/null
+++ b/feature-detects/window/resizeobserver.js
@@ -0,0 +1,29 @@
+/*!
+{
+  "name": "ResizeObserver",
+  "property": "resizeobserver",
+  "caniuse": "resizeobserver",
+  "tags": ["ResizeObserver"],
+  "authors": ["Christian Andersson"],
+  "notes": [{
+    "name": "W3C Spec",
+    "href": "https://www.w3.org/TR/resize-observer/"
+  }, {
+    "name": "MDN Docs",
+    "href": "https://developer.mozilla.org/en-US/docs/Web/API/ResizeObserver"
+  }, {
+    "name": "Web.dev Article",
+    "href": "https://web.dev/resize-observer/"
+  }, {
+    "name": "Digital Ocean tutorial",
+    "href": "https://www.digitalocean.com/community/tutorials/js-resize-observer"
+  }]
+}
+!*/
+
+/* DOC
+Detects support for ResizeObserver.
+*/
+define(['Modernizr'], function(Modernizr) {
+  Modernizr.addTest('resizeobserver', 'ResizeObserver' in window);
+});
diff --git a/lib/config-all.json b/lib/config-all.json
index db4cf435..60ab7d74 100644
--- a/lib/config-all.json
+++ b/lib/config-all.json
@@ -310,6 +310,7 @@
     "window/atob-btoa",
     "window/framed",
     "window/matchmedia",
+    "window/resizeobserver",
     "workers/blobworkers",
     "workers/dataworkers",
     "workers/sharedworkers",


Test patch:
diff --git a/test/browser/integration/caniuse.js b/test/browser/integration/caniuse.js
index 60259ba1..c4fabe10 100644
--- a/test/browser/integration/caniuse.js
+++ b/test/browser/integration/caniuse.js
@@ -130,6 +130,7 @@ window.caniusecb = function(caniuse) {
       queryselector: 'queryselector',
       regions: 'css-regions',
       requestanimationframe: 'requestanimationframe',
+      resizeobserver: 'resizeobserver',
       rgba: 'css3-colors',
       ruby: 'ruby',
       sandbox: 'iframe-sandbox',