AK: Remove fatal() from InputStream.

Fatal errors can not be handeled and lead to an assertion error when the
stream is destroyed. It makes no sense to delay the assertion failure,
instead of setting m_fatal, an assertion should be done directly.

AK/Stream.h

@@ -37,17 +37,15 @@ class Stream {
 public:
     virtual ~Stream()
     {
-        ASSERT(!error() && !fatal());
+        ASSERT(!error());
     }
 
     bool error() const { return m_error; }
-    bool fatal() const { return m_fatal; }
 
     bool handle_error() { return exchange(m_error, false); }
 
 protected:
     mutable bool m_error { false };
-    mutable bool m_fatal { false };
 };
 
 }