Remove include only fwl.h and IWYU.

xfa/include/fwl/core/fwl_theme.h

Index: xfa/include/fwl/core/fwl_theme.h
diff --git a/xfa/include/fwl/core/fwl_theme.h b/xfa/include/fwl/core/fwl_theme.h
index 2700e3bd55eb3f48603f99ba452436f0cd604e01..8f9f9a6c368c2f5ea305e5e3971adfded0335ce1 100644
--- a/xfa/include/fwl/core/fwl_theme.h
+++ b/xfa/include/fwl/core/fwl_theme.h
@@ -7,12 +7,11 @@
 #ifndef XFA_INCLUDE_FWL_CORE_FWL_THEME_H_
 #define XFA_INCLUDE_FWL_CORE_FWL_THEME_H_
 
+#include "xfa/include/fwl/core/fwl_error.h"
+#include "xfa/include/fxgraphics/fx_graphics.h"
+
 class IFWL_Widget;
-class CFWL_ThemePart;
-class CFWL_ThemeBackground;
-class CFWL_ThemeText;
-class CFWL_ThemeElement;
-class IFWL_ThemeProvider;
+
 #define FWL_WGTCAPACITY_CXBorder 1
 #define FWL_WGTCAPACITY_CYBorder 2
 #define FWL_WGTCAPACITY_ScrollBarWidth 3
@@ -27,6 +26,7 @@ class IFWL_ThemeProvider;
 #define FWL_WGTCAPACITY_UIMargin 12
 #define FWL_WGTCAPACITY_SpaceAboveBelow 13
 #define FWL_WGTCAPACITY_MAX 65535
+
 class CFWL_ThemePart {
  public:
   CFWL_ThemePart()