Backport Basilisk internal userscripts

browser/internaluserscripts/bundled-scripts/elementfrompoint-finite-polyfill.user.js

@@ -0,0 +1,93 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+// ==UserScript==
+// @name         elementFromPoint finite-args shim
+// @namespace    internal-userscripts
+// @description  Prevents throws when Document.elementFromPoint / elementsFromPoint receives non-finite coordinates.
+// @match        *://*/*
+// @grant        none
+// @run-at       document-start
+// ==/UserScript==
+(function () {
+  "use strict";
+
+  var global = typeof window !== "undefined" ? window : null;
+  if (!global || !global.Document || !global.Document.prototype) {
+    return;
+  }
+
+  var patched = false;
+
+  function toFiniteNumber(value) {
+    var number = Number(value);
+    if (number !== number || number === Infinity || number === -Infinity) {
+      return null;
+    }
+    return number;
+  }
+
+  function fallbackValue(methodName) {
+    return methodName === "elementsFromPoint" ? [] : null;
+  }
+
+  function wrapMethod(proto, methodName) {
+    var nativeMethod = proto[methodName];
+    if (typeof nativeMethod !== "function") {
+      return;
+    }
+    if (nativeMethod.__internalUserscriptsFinitePointShim) {
+      return;
+    }
+
+    function wrappedMethod(x, y) {
+      var finiteX = toFiniteNumber(x);
+      var finiteY = toFiniteNumber(y);
+      if (finiteX === null || finiteY === null) {
+        return fallbackValue(methodName);
+      }
+
+      try {
+        return nativeMethod.call(this, finiteX, finiteY);
+      } catch (e) {
+        var message = e && e.message ? String(e.message) : "";
+        if (message.indexOf("not a finite floating-point value") !== -1 ||
+            message.indexOf("is not finite") !== -1) {
+          return fallbackValue(methodName);
+        }
+        throw e;
+      }
+    }
+
+    try {
+      Object.defineProperty(wrappedMethod, "__internalUserscriptsFinitePointShim", {
+        value: true
+      });
+    } catch (e) {}
+
+    try {
+      Object.defineProperty(proto, methodName, {
+        value: wrappedMethod,
+        writable: true,
+        configurable: true
+      });
+    } catch (e) {
+      try {
+        proto[methodName] = wrappedMethod;
+      } catch (ignore) {}
+    }
+
+    if (proto[methodName] === wrappedMethod) {
+      patched = true;
+    }
+  }
+
+  wrapMethod(global.Document.prototype, "elementFromPoint");
+  wrapMethod(global.Document.prototype, "elementsFromPoint");
+
+  if (patched) {
+    try {
+      global.__internalUserscriptsElementFromPointFinitePolyfill = true;
+    } catch (e) {}
+  }
+})();