LibWeb: Use JS::HeapFunction for callbacks in FetchController

If a function that captures a GC-allocated object is owned by another
GC-allocated object, it is more preferable to use JS::HeapFunction.
This is because JS::HeapFunction is visited, unlike introducing a new
heap root as JS::SafeFunction does.

Userland/Libraries/LibWeb/Fetch/Infrastructure/FetchController.cpp

@@ -24,27 +24,39 @@ void FetchController::visit_edges(JS::Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);
     visitor.visit(m_full_timing_info);
+    visitor.visit(m_report_timing_steps);
+    visitor.visit(m_next_manual_redirect_steps);
     visitor.visit(m_fetch_params);
 }
 
+void FetchController::set_report_timing_steps(Function<void(JS::Object const&)> report_timing_steps)
+{
+    m_report_timing_steps = JS::create_heap_function(vm().heap(), move(report_timing_steps));
+}
+
+void FetchController::set_next_manual_redirect_steps(Function<void()> next_manual_redirect_steps)
+{
+    m_next_manual_redirect_steps = JS::create_heap_function(vm().heap(), move(next_manual_redirect_steps));
+}
+
 // https://fetch.spec.whatwg.org/#finalize-and-report-timing
 void FetchController::report_timing(JS::Object const& global) const
 {
     // 1. Assert: this’s report timing steps is not null.
-    VERIFY(m_report_timing_steps.has_value());
+    VERIFY(m_report_timing_steps);
 
     // 2. Call this’s report timing steps with global.
-    (*m_report_timing_steps)(global);
+    m_report_timing_steps->function()(global);
 }
 
 // https://fetch.spec.whatwg.org/#fetch-controller-process-the-next-manual-redirect
 void FetchController::process_next_manual_redirect() const
 {
     // 1. Assert: controller’s next manual redirect steps are not null.
-    VERIFY(m_next_manual_redirect_steps.has_value());
+    VERIFY(m_next_manual_redirect_steps);
 
     // 2. Call controller’s next manual redirect steps.
-    (*m_next_manual_redirect_steps)();
+    m_next_manual_redirect_steps->function()();
 }
 
 // https://fetch.spec.whatwg.org/#extract-full-timing-info

Userland/Libraries/LibWeb/Fetch/Infrastructure/FetchController.h

@@ -10,6 +10,8 @@
 #include <LibJS/Forward.h>
 #include <LibJS/Heap/Cell.h>
 #include <LibJS/Heap/GCPtr.h>
+#include <LibJS/Heap/HeapFunction.h>
+#include <LibJS/Runtime/VM.h>
 #include <LibJS/SafeFunction.h>
 #include <LibWeb/Fetch/Infrastructure/FetchTimingInfo.h>
 #include <LibWeb/Forward.h>
@@ -30,8 +32,8 @@ public:
     [[nodiscard]] static JS::NonnullGCPtr<FetchController> create(JS::VM&);
 
     void set_full_timing_info(JS::NonnullGCPtr<FetchTimingInfo> full_timing_info) { m_full_timing_info = full_timing_info; }
-    void set_report_timing_steps(JS::SafeFunction<void(JS::Object const&)> report_timing_steps) { m_report_timing_steps = move(report_timing_steps); }
+    void set_report_timing_steps(Function<void(JS::Object const&)> report_timing_steps);
-    void set_next_manual_redirect_steps(JS::SafeFunction<void()> next_manual_redirect_steps) { m_next_manual_redirect_steps = move(next_manual_redirect_steps); }
+    void set_next_manual_redirect_steps(Function<void()> next_manual_redirect_steps);
 
     [[nodiscard]] State state() const { return m_state; }
 
@@ -63,7 +65,7 @@ private:
     // https://fetch.spec.whatwg.org/#fetch-controller-report-timing-steps
     // report timing steps (default null)
     //    Null or an algorithm accepting a global object.
-    Optional<JS::SafeFunction<void(JS::Object const&)>> m_report_timing_steps;
+    JS::GCPtr<JS::HeapFunction<void(JS::Object const&)>> m_report_timing_steps;
 
     // https://fetch.spec.whatwg.org/#fetch-controller-report-timing-steps
     // FIXME: serialized abort reason (default null)
@@ -72,7 +74,7 @@ private:
     // https://fetch.spec.whatwg.org/#fetch-controller-next-manual-redirect-steps
     // next manual redirect steps (default null)
     //     Null or an algorithm accepting nothing.
-    Optional<JS::SafeFunction<void()>> m_next_manual_redirect_steps;
+    JS::GCPtr<JS::HeapFunction<void()>> m_next_manual_redirect_steps;
 
     JS::GCPtr<FetchParams> m_fetch_params;
 };