LibWebView: Don't re-create WebContent proceses when repeatedly crashing

Serenity handles this in the SystemServer already, but the simplest
place to put this logic is the ViewImplementation base class.

This is trivial to see when running Ladybird without SERENTIY_SOURCE_DIR
set, or set improperly.

Userland/Libraries/LibWebView/ViewImplementation.h

@@ -200,6 +200,9 @@ protected:
 
     RefPtr<Gfx::Bitmap> m_backup_bitmap;
     Gfx::IntSize m_backup_bitmap_size;
+
+    size_t m_crash_count = 0;
+    RefPtr<Core::Timer> m_repeated_crash_timer;
 };
 
 }