Make animated image playback speed match browser (Firefox and Chrome) behaviour (#3506)

Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>
Co-authored-by: Paweł <zneix@zneix.eu>

src/messages/Image.cpp

@@ -152,8 +152,15 @@ namespace detail {
             if (reader.read(&image))
             {
                 QPixmap::fromImage(image);
-
-                int duration = std::max(20, reader.nextImageDelay());
+                // It seems that browsers have special logic for fast animations.
+                // This implements Chrome and Firefox's behavior which uses
+                // a duration of 100 ms for any frames that specify a duration of <= 10 ms.
+                // See http://webkit.org/b/36082 for more information.
+                // https://github.com/SevenTV/chatterino7/issues/46#issuecomment-1010595231
+                int duration = reader.nextImageDelay();
+                if (duration <= 10)
+                    duration = 100;
+                duration = std::max(20, duration);
                 frames.push_back(Frame<QImage>{image, duration});
             }
         }