LibGfx: Revert #2154 and properly handle simple polygons

The existing scanline method works just fine, and only needs the points
to be available as floats.
This commit reverts the complex polygon mitigation, and instead fixes
the rasterization process to avoid generating complex polygons because
of precision issues.

Libraries/LibGfx/Painter.cpp

@@ -1154,7 +1154,7 @@ void Painter::stroke_path(const Path& path, Color color, int thickness)
 
 void Painter::fill_path(Path& path, Color color, WindingRule winding_rule)
 {
-    const auto& segments = path.split_lines(Path::Simple);
+    const auto& segments = path.split_lines();
 
     if (segments.size() == 0)
         return;