diff --git a/css/properties/-webkit-mask-box-image-outset.json b/css/properties/-webkit-mask-box-image-outset.json
deleted file mode 100644
index 6bf1879985c3fe..00000000000000
--- a/css/properties/-webkit-mask-box-image-outset.json
+++ /dev/null
@@ -1,39 +0,0 @@
-{
-  "css": {
-    "properties": {
-      "-webkit-mask-box-image-outset": {
-        "__compat": {
-          "support": {
-            "chrome": {
-              "version_added": "≤80"
-            },
-            "chrome_android": "mirror",
-            "edge": "mirror",
-            "firefox": {
-              "version_added": false
-            },
-            "firefox_android": "mirror",
-            "ie": {
-              "version_added": false
-            },
-            "oculus": "mirror",
-            "opera": "mirror",
-            "opera_android": "mirror",
-            "safari": {
-              "version_added": "≤13.1"
-            },
-            "safari_ios": "mirror",
-            "samsunginternet_android": "mirror",
-            "webview_android": "mirror",
-            "webview_ios": "mirror"
-          },
-          "status": {
-            "experimental": false,
-            "standard_track": true,
-            "deprecated": false
-          }
-        }
-      }
-    }
-  }
-}
diff --git a/css/properties/-webkit-mask-box-image-repeat.json b/css/properties/-webkit-mask-box-image-repeat.json
deleted file mode 100644
index b5bfe3cca9e1d1..00000000000000
--- a/css/properties/-webkit-mask-box-image-repeat.json
+++ /dev/null
@@ -1,39 +0,0 @@
-{
-  "css": {
-    "properties": {
-      "-webkit-mask-box-image-repeat": {
-        "__compat": {
-          "support": {
-            "chrome": {
-              "version_added": "≤80"
-            },
-            "chrome_android": "mirror",
-            "edge": "mirror",
-            "firefox": {
-              "version_added": false
-            },
-            "firefox_android": "mirror",
-            "ie": {
-              "version_added": false
-            },
-            "oculus": "mirror",
-            "opera": "mirror",
-            "opera_android": "mirror",
-            "safari": {
-              "version_added": "≤13.1"
-            },
-            "safari_ios": "mirror",
-            "samsunginternet_android": "mirror",
-            "webview_android": "mirror",
-            "webview_ios": "mirror"
-          },
-          "status": {
-            "experimental": false,
-            "standard_track": true,
-            "deprecated": false
-          }
-        }
-      }
-    }
-  }
-}
diff --git a/css/properties/-webkit-mask-box-image-slice.json b/css/properties/-webkit-mask-box-image-slice.json
deleted file mode 100644
index 06db8f5cf1c581..00000000000000
--- a/css/properties/-webkit-mask-box-image-slice.json
+++ /dev/null
@@ -1,39 +0,0 @@
-{
-  "css": {
-    "properties": {
-      "-webkit-mask-box-image-slice": {
-        "__compat": {
-          "support": {
-            "chrome": {
-              "version_added": "≤80"
-            },
-            "chrome_android": "mirror",
-            "edge": "mirror",
-            "firefox": {
-              "version_added": false
-            },
-            "firefox_android": "mirror",
-            "ie": {
-              "version_added": false
-            },
-            "oculus": "mirror",
-            "opera": "mirror",
-            "opera_android": "mirror",
-            "safari": {
-              "version_added": "≤13.1"
-            },
-            "safari_ios": "mirror",
-            "samsunginternet_android": "mirror",
-            "webview_android": "mirror",
-            "webview_ios": "mirror"
-          },
-          "status": {
-            "experimental": false,
-            "standard_track": true,
-            "deprecated": false
-          }
-        }
-      }
-    }
-  }
-}
diff --git a/css/properties/-webkit-mask-box-image-source.json b/css/properties/-webkit-mask-box-image-source.json
deleted file mode 100644
index 1b080f264f3206..00000000000000
--- a/css/properties/-webkit-mask-box-image-source.json
+++ /dev/null
@@ -1,39 +0,0 @@
-{
-  "css": {
-    "properties": {
-      "-webkit-mask-box-image-source": {
-        "__compat": {
-          "support": {
-            "chrome": {
-              "version_added": "≤80"
-            },
-            "chrome_android": "mirror",
-            "edge": "mirror",
-            "firefox": {
-              "version_added": false
-            },
-            "firefox_android": "mirror",
-            "ie": {
-              "version_added": false
-            },
-            "oculus": "mirror",
-            "opera": "mirror",
-            "opera_android": "mirror",
-            "safari": {
-              "version_added": "≤13.1"
-            },
-            "safari_ios": "mirror",
-            "samsunginternet_android": "mirror",
-            "webview_android": "mirror",
-            "webview_ios": "mirror"
-          },
-          "status": {
-            "experimental": false,
-            "standard_track": true,
-            "deprecated": false
-          }
-        }
-      }
-    }
-  }
-}
diff --git a/css/properties/-webkit-mask-box-image-width.json b/css/properties/-webkit-mask-box-image-width.json
deleted file mode 100644
index acbe19679b9cc2..00000000000000
--- a/css/properties/-webkit-mask-box-image-width.json
+++ /dev/null
@@ -1,39 +0,0 @@
-{
-  "css": {
-    "properties": {
-      "-webkit-mask-box-image-width": {
-        "__compat": {
-          "support": {
-            "chrome": {
-              "version_added": "≤80"
-            },
-            "chrome_android": "mirror",
-            "edge": "mirror",
-            "firefox": {
-              "version_added": false
-            },
-            "firefox_android": "mirror",
-            "ie": {
-              "version_added": false
-            },
-            "oculus": "mirror",
-            "opera": "mirror",
-            "opera_android": "mirror",
-            "safari": {
-              "version_added": "≤13.1"
-            },
-            "safari_ios": "mirror",
-            "samsunginternet_android": "mirror",
-            "webview_android": "mirror",
-            "webview_ios": "mirror"
-          },
-          "status": {
-            "experimental": false,
-            "standard_track": true,
-            "deprecated": false
-          }
-        }
-      }
-    }
-  }
-}