LibWeb: Revert blocking of task by source in EventLoop

This reverts commit 664611bae41a20d3bf740da12fdf19322f6574f1.

It seems like the HTML spec has been misinterpreted and this text:
"... Note that in this setup, the processing model still enforces that
the user agent would never process events from any one task source out
of order."

does not mean we can't interrupt execution of task by a task with the
same task source. It just says they should be processed in the order
they were added.

Fixes hanging while navigating from PR list to PR page on GitHub.

Userland/Libraries/LibWeb/HTML/EventLoop/EventLoop.cpp

@@ -27,9 +27,6 @@ EventLoop::EventLoop()
 {
     m_task_queue = heap().allocate_without_realm<TaskQueue>(*this);
     m_microtask_queue = heap().allocate_without_realm<TaskQueue>(*this);
-
-    for (size_t i = 0; i < m_blocked_task_sources.size(); ++i)
-        m_blocked_task_sources[i] = false;
 }
 
 EventLoop::~EventLoop() = default;
@@ -62,31 +59,6 @@ EventLoop& main_thread_event_loop()
     return *static_cast<Bindings::WebEngineCustomData*>(Bindings::main_thread_vm().custom_data())->event_loop;
 }
 
-bool EventLoop::is_task_source_blocked(Task::Source source) const
-{
-    if (source == Task::Source::Unspecified)
-        return false;
-    if (static_cast<size_t>(to_underlying(source)) < m_blocked_task_sources.size())
-        return m_blocked_task_sources[to_underlying(source)];
-    return false;
-}
-
-void EventLoop::block_task_source(Task::Source source)
-{
-    if (source == Task::Source::Unspecified)
-        return;
-    if (static_cast<size_t>(to_underlying(source)) < m_blocked_task_sources.size())
-        m_blocked_task_sources[to_underlying(source)] = true;
-}
-
-void EventLoop::unblock_task_source(Task::Source source)
-{
-    if (source == Task::Source::Unspecified)
-        return;
-    if (static_cast<size_t>(to_underlying(source)) < m_blocked_task_sources.size())
-        m_blocked_task_sources[to_underlying(source)] = false;
-}
-
 // https://html.spec.whatwg.org/multipage/webappapis.html#spin-the-event-loop
 void EventLoop::spin_until(JS::SafeFunction<bool()> goal_condition)
 {
@@ -147,13 +119,11 @@ void EventLoop::spin_processing_tasks_with_source_until(Task::Source source, JS:
                 return task.source() == source && task.is_runnable();
             });
 
-            block_task_source(source);
             for (auto& task : tasks) {
                 m_currently_running_task = task.ptr();
                 task->execute();
                 m_currently_running_task = nullptr;
             }
-            unblock_task_source(source);
         }
 
         // FIXME: Remove the platform event loop plugin so that this doesn't look out of place
@@ -191,8 +161,6 @@ void EventLoop::process()
     oldest_task = task_queue.take_first_runnable();
 
     if (oldest_task) {
-        block_task_source(oldest_task->source());
-
         // 5. Set the event loop's currently running task to oldestTask.
         m_currently_running_task = oldest_task.ptr();
 
@@ -201,8 +169,6 @@ void EventLoop::process()
 
         // 7. Set the event loop's currently running task back to null.
         m_currently_running_task = nullptr;
-
-        unblock_task_source(oldest_task->source());
     }
 
     // 8. Microtasks: Perform a microtask checkpoint.

Userland/Libraries/LibWeb/HTML/EventLoop/EventLoop.h

@@ -39,10 +39,6 @@ public:
     TaskQueue& microtask_queue() { return *m_microtask_queue; }
     TaskQueue const& microtask_queue() const { return *m_microtask_queue; }
 
-    bool is_task_source_blocked(Task::Source source) const;
-    void block_task_source(Task::Source source);
-    void unblock_task_source(Task::Source source);
-
     void spin_until(NOESCAPE JS::SafeFunction<bool()> goal_condition);
     void spin_processing_tasks_with_source_until(Task::Source, NOESCAPE JS::SafeFunction<bool()> goal_condition);
     void process();
@@ -117,8 +113,6 @@ private:
     bool m_execution_paused { false };
 
     bool m_skip_event_loop_processing_steps { false };
-
-    Array<bool, to_underlying(Task::Source::UniqueTaskSourceStart)> m_blocked_task_sources;
 };
 
 EventLoop& main_thread_event_loop();

Userland/Libraries/LibWeb/HTML/EventLoop/TaskQueue.cpp

@@ -39,10 +39,7 @@ JS::GCPtr<Task> TaskQueue::take_first_runnable()
         return nullptr;
 
     for (size_t i = 0; i < m_tasks.size(); ++i) {
-        auto const& task = m_tasks[i];
-        if (m_event_loop->is_task_source_blocked(task->source()))
-            continue;
-        if (task->is_runnable())
+        if (m_tasks[i]->is_runnable())
             return m_tasks.take(i);
     }
     return nullptr;
@@ -54,8 +51,6 @@ bool TaskQueue::has_runnable_tasks() const
         return false;
 
     for (auto& task : m_tasks) {
-        if (m_event_loop->is_task_source_blocked(task->source()))
-            continue;
         if (task->is_runnable())
             return true;
     }