LibJS: Add inline caching for adding new own properties to objects

We already had IC support in PutById for the following cases:
- Changing an existing own property
- Calling a setter located in the prototype chain

This was enough to speed up code where structurally identical objects
(same shape) are processed in a loop:
```js
const arr = [{ a: 1 }, { a: 2 }, { a: 3 }];
for (let obj of arr) {
    obj.a += 1;
}
```

However, creating structurally identical objects in a loop was still
slow:
```js
for (let i = 0; i < 10_000_000; i++) {
    const o = {};
    o.a = 1;
    o.b = 2;
    o.c = 3;
}
```

This change addresses that by adding a new IC type that caches both the
source and target shapes, allowing property additions to be fast-pathed
by directly jumping to the shape that already includes the new property.

Libraries/LibWeb/HTML/WindowProxy.cpp

@@ -154,7 +154,7 @@ JS::ThrowCompletionOr<bool> WindowProxy::internal_define_own_property(JS::Proper
 
 // 7.4.7 [[Get]] ( P, Receiver ), https://html.spec.whatwg.org/multipage/nav-history-apis.html#windowproxy-get
 // https://html.spec.whatwg.org/multipage/nav-history-apis.html#windowproxy-get
-JS::ThrowCompletionOr<JS::Value> WindowProxy::internal_get(JS::PropertyKey const& property_key, JS::Value receiver, JS::CacheablePropertyMetadata*, PropertyLookupPhase) const
+JS::ThrowCompletionOr<JS::Value> WindowProxy::internal_get(JS::PropertyKey const& property_key, JS::Value receiver, JS::CacheableGetPropertyMetadata*, PropertyLookupPhase) const
 {
     auto& vm = this->vm();
 
@@ -175,7 +175,7 @@ JS::ThrowCompletionOr<JS::Value> WindowProxy::internal_get(JS::PropertyKey const
 
 // 7.4.8 [[Set]] ( P, V, Receiver ), https://html.spec.whatwg.org/multipage/nav-history-apis.html#windowproxy-set
 // https://html.spec.whatwg.org/multipage/nav-history-apis.html#windowproxy-set
-JS::ThrowCompletionOr<bool> WindowProxy::internal_set(JS::PropertyKey const& property_key, JS::Value value, JS::Value receiver, JS::CacheablePropertyMetadata*, PropertyLookupPhase)
+JS::ThrowCompletionOr<bool> WindowProxy::internal_set(JS::PropertyKey const& property_key, JS::Value value, JS::Value receiver, JS::CacheableSetPropertyMetadata*, PropertyLookupPhase)
 {
     auto& vm = this->vm();