Add background-repeat-{x,y} (#27368)

Author: Elchi3

css/properties/background-repeat-x.json

@@ -0,0 +1,37 @@
+{
+  "css": {
+    "properties": {
+      "background-repeat-x": {
+        "__compat": {
+          "spec_url": "https://drafts.csswg.org/css-backgrounds-4/#background-repeat-longhands",
+          "support": {
+            "chrome": {
+              "version_added": false
+            },
+            "chrome_android": "mirror",
+            "edge": "mirror",
+            "firefox": {
+              "version_added": false
+            },
+            "firefox_android": "mirror",
+            "oculus": "mirror",
+            "opera": "mirror",
+            "opera_android": "mirror",
+            "safari": {
+              "version_added": "5"
+            },
+            "safari_ios": "mirror",
+            "samsunginternet_android": "mirror",
+            "webview_android": "mirror",
+            "webview_ios": "mirror"
+          },
+          "status": {
+            "experimental": true,
+            "standard_track": true,
+            "deprecated": false
+          }
+        }
+      }
+    }
+  }
+}

css/properties/background-repeat-y.json

@@ -0,0 +1,37 @@
+{
+  "css": {
+    "properties": {
+      "background-repeat-y": {
+        "__compat": {
+          "spec_url": "https://drafts.csswg.org/css-backgrounds-4/#background-repeat-longhands",
+          "support": {
+            "chrome": {
+              "version_added": false
+            },
+            "chrome_android": "mirror",
+            "edge": "mirror",
+            "firefox": {
+              "version_added": false
+            },
+            "firefox_android": "mirror",
+            "oculus": "mirror",
+            "opera": "mirror",
+            "opera_android": "mirror",
+            "safari": {
+              "version_added": "5"
+            },
+            "safari_ios": "mirror",
+            "samsunginternet_android": "mirror",
+            "webview_android": "mirror",
+            "webview_ios": "mirror"
+          },
+          "status": {
+            "experimental": true,
+            "standard_track": true,
+            "deprecated": false
+          }
+        }
+      }
+    }
+  }
+}