LibJS: Add ECMA-262 section/title/URL comments almost everywhere

As mentioned on Discord earlier, we'll add these to all new functions
going forward - this is the backfill. Reasons:

- It makes you look at the spec, implementing based on MDN or V8
  behavior is a no-go
- It makes finding the various functions that are non-compliant easier,
  in the future everything should either have such a comment or, if it's
  not from the spec at all, a comment explaining why that is the case
- It makes it easier to check whether a certain abstract operation is
  implemented in LibJS, not all of them use the same name as the spec.
  E.g. RejectPromise() is Promise::reject()
- It makes it easier to reason about vm.arguments(), e.g. when the
  function has a rest parameter
- It makes it easier to see whether a certain function is from a
  proposal or Annex B

Also:

- Add arguments to all functions and abstract operations that already
  had a comment
- Fix some outdated section numbers
- Replace some ecma-international.org URLs with tc39.es

Userland/Libraries/LibJS/Runtime/WeakRefConstructor.cpp

@@ -20,7 +20,10 @@ void WeakRefConstructor::initialize(GlobalObject& global_object)
 {
     auto& vm = this->vm();
     NativeFunction::initialize(global_object);
+
+    // 26.1.2.1 WeakRef.prototype, https://tc39.es/ecma262/#sec-weak-ref.prototype
     define_property(vm.names.prototype, global_object.weak_ref_prototype(), 0);
+
     define_property(vm.names.length, Value(1), Attribute::Configurable);
 }
 
@@ -28,6 +31,7 @@ WeakRefConstructor::~WeakRefConstructor()
 {
 }
 
+// 26.1.1.1 WeakRef ( target ), https://tc39.es/ecma262/#sec-weak-ref-target
 Value WeakRefConstructor::call()
 {
     auto& vm = this->vm();