Add trusted-override-element-method scriptlet

@description
Override the behavior of a method on matching elements.

@param methodPath
The method which calls must be intercepted.

@param [selector]
A CSS selector which the target element must match. If not specified,
the override will occur for all elements.

@param [disposition]
How the override should be handled. If not specified, the overridden call
will be equivalent to an empty function. If set to `throw`, an exception
will be thrown. Any other value will be validated and returned as a
supported safe constant.

@example
..##+js(trusted-override-element-method, HTMLAnchorElement.prototype.click, a[target="_blank"][style])

Author: gorhill

assets/resources/scriptlets.js

@@ -5218,4 +5218,68 @@ function trustedPreventDomBypass(
     });
 }
 
+/**
+ * 
+ * @trustedScriptlet trusted-override-element-method
+ * 
+ * @description
+ * Override the behavior of a method on matching elements.
+ * 
+ * @param methodPath
+ * The method which calls must be intercepted.
+ * 
+ * @param [selector]
+ * A CSS selector which the target element must match. If not specified,
+ * the override will occur for all elements.
+ * 
+ * @param [disposition]
+ * How the override should be handled. If not specified, the overridden call
+ * will be equivalent to an empty function. If set to `throw`, an exception
+ * will be thrown. Any other value will be validated and returned as a
+ * supported safe constant.
+ * 
+ * @example
+ * ##+js(trusted-override-element-method, HTMLAnchorElement.prototype.click, a[target="_blank"][style])
+ * 
+ * */
+
+builtinScriptlets.push({
+    name: 'trusted-override-element-method.js',
+    requiresTrust: true,
+    fn: trustedOverrideElementMethod,
+    dependencies: [
+        'proxy-apply.fn',
+        'safe-self.fn',
+        'validate-constant.fn',
+    ],
+});
+function trustedOverrideElementMethod(
+    methodPath = '',
+    selector = '',
+    disposition = ''
+) {
+    if ( methodPath === '' ) { return; }
+    const safe = safeSelf();
+    const logPrefix = safe.makeLogPrefix('trusted-override-element-method', methodPath, selector, disposition);
+    proxyApplyFn(methodPath, function(context) {
+        let override = selector === '';
+        if ( override === false ) {
+            const { thisArg } = context;
+            try {
+                override = thisArg.closest(selector) === thisArg;
+            } catch(_) {
+            }
+        }
+        if ( override === false ) {
+            return context.reflect();
+        }
+        safe.uboLog(logPrefix, 'Overridden');
+        if ( disposition === '' ) { return; }
+        if ( disposition === 'throw' ) {
+            throw new ReferenceError();
+        }
+        return validateConstantFn(false, disposition);
+    });
+}
+
 /******************************************************************************/