Delete api.HTMLFrameSetElement.onstorage (#15158)

* Adapt api.HTMLFrameSetElement.onstorage to new events structure

This PR adapts the storage event of the HTMLFrameSetElement API to conform to the new events structure.

Note: there are no MDN pages associated with these events, so there will be no corresponding content PR. Any broken MDN URLs in BCD have been removed.

* Remove storage_event (deferred to another PR)

api/HTMLFrameSetElement.json

@@ -95,53 +95,6 @@
           }
         }
       },
-      "onstorage": {
-        "__compat": {
-          "support": {
-            "chrome": {
-              "version_added": "3"
-            },
-            "chrome_android": {
-              "version_added": "18"
-            },
-            "edge": {
-              "version_added": "12"
-            },
-            "firefox": {
-              "version_added": "45"
-            },
-            "firefox_android": {
-              "version_added": "45"
-            },
-            "ie": {
-              "version_added": "9"
-            },
-            "opera": {
-              "version_added": "15"
-            },
-            "opera_android": {
-              "version_added": "14"
-            },
-            "safari": {
-              "version_added": "4"
-            },
-            "safari_ios": {
-              "version_added": "3.2"
-            },
-            "samsunginternet_android": {
-              "version_added": "1.0"
-            },
-            "webview_android": {
-              "version_added": "≤37"
-            }
-          },
-          "status": {
-            "experimental": false,
-            "standard_track": true,
-            "deprecated": true
-          }
-        }
-      },
       "rows": {
         "__compat": {
           "support": {