Minimize memory allocation in scriptlet helper proxy-apply-fn

Probably beneficial in cases of proxied method called in a tight loop. Additionally, added `throwFunc` as valid constant in script helper `validate-constant.fn`. Does what the name implies.

Author: gorhill

assets/resources/scriptlets.js

@@ -535,6 +535,8 @@ function validateConstantFn(trusted, raw, extraArgs = {}) {
  value = function(){ return true; };
  } else if ( raw === 'falseFunc' ) {
  value = function(){ return false; };
+ } else if ( raw === 'throwFunc' ) {
+ value = function(){ throw ''; };
  } else if ( /^-?\d+$/.test(raw) ) {
  value = parseInt(raw);
  if ( isNaN(raw) ) { return; }
@@ -1498,31 +1500,57 @@ function proxyApplyFn(
  const fn = context[prop];
  if ( typeof fn !== 'function' ) { return; }
  if ( proxyApplyFn.CtorContext === undefined ) {
+ proxyApplyFn.ctorContexts = [];
  proxyApplyFn.CtorContext = class {
- constructor(callFn, callArgs) {
+ constructor(...args) {
+ this.init(...args);
+ }
+ init(callFn, callArgs) {
  this.callFn = callFn;
  this.callArgs = callArgs;
+ return this;
  }
  reflect() {
- return Reflect.construct(this.callFn, this.callArgs);
+ const r = Reflect.construct(this.callFn, this.callArgs);
+ this.callFn = this.callArgs = undefined;
+ proxyApplyFn.ctorContexts.push(this);
+ return r;
+ }
+ static factory(...args) {
+ return proxyApplyFn.ctorContexts.length !== 0
+ ? proxyApplyFn.ctorContexts.pop().init(...args)
+ : new proxyApplyFn.CtorContext(...args);
  }
  };
+ proxyApplyFn.applyContexts = [];
  proxyApplyFn.ApplyContext = class {
- constructor(callFn, thisArg, callArgs) {
+ constructor(...args) {
+ this.init(...args);
+ }
+ init(callFn, thisArg, callArgs) {
  this.callFn = callFn;
  this.thisArg = thisArg;
  this.callArgs = callArgs;
+ return this;
  }
  reflect() {
- return Reflect.apply(this.callFn, this.thisArg, this.callArgs);
+ const r = Reflect.apply(this.callFn, this.thisArg, this.callArgs);
+ this.callFn = this.thisArg = this.callArgs = undefined;
+ proxyApplyFn.applyContexts.push(this);
+ return r;
+ }
+ static factory(...args) {
+ return proxyApplyFn.applyContexts.length !== 0
+ ? proxyApplyFn.applyContexts.pop().init(...args)
+ : new proxyApplyFn.ApplyContext(...args);
  }
  };
  }
  const fnStr = fn.toString();
  const toString = (function toString() { return fnStr; }).bind(null);
  const proxyDetails = {
  apply(target, thisArg, args) {
- return handler(new proxyApplyFn.ApplyContext(target, thisArg, args));
+ return handler(proxyApplyFn.ApplyContext.factory(target, thisArg, args));
  },
  get(target, prop) {
  if ( prop === 'toString' ) { return toString; }
@@ -1531,7 +1559,7 @@ function proxyApplyFn(
  };
  if ( fn.prototype?.constructor === fn ) {
  proxyDetails.construct = function(target, args) {
- return handler(new proxyApplyFn.CtorContext(target, args));
+ return handler(proxyApplyFn.CtorContext.factory(target, args));
  };
  }
  context[prop] = new Proxy(fn, proxyDetails);