reset imp_url to impl_url

Author: dletorey

css/types/attr.json

@@ -56,7 +56,7 @@
             "support": {
               "chrome": {
                 "version_added": false,
-                "imp_url": "https://crbug.com/387281256"
+                "impl_url": "https://crbug.com/387281256"
               },
               "chrome_android": "mirror",
               "edge": "mirror",
@@ -76,7 +76,7 @@
               "opera_android": "mirror",
               "safari": {
                 "version_added": false,
-                "imp_url": "https://webkit.org/b/283279"
+                "impl_url": "https://webkit.org/b/283279"
               },
               "safari_ios": "mirror",
               "samsunginternet_android": "mirror",