Initialize more fwl classes in header.

Provide initializers for scalars even if we think they will be changed
before use. Tidy/pack while at it, prefer scalars with initializers
before classes which initialize themselves.

Change-Id: If766cbc3445222e0eeb1676be73e6ca88282974c
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/65012
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/xfa/fwl/cfwl_eventtarget.h b/xfa/fwl/cfwl_eventtarget.h
index b5a8bdb..f614319 100644
--- a/xfa/fwl/cfwl_eventtarget.h
+++ b/xfa/fwl/cfwl_eventtarget.h
@@ -26,9 +26,9 @@
   void FlagInvalid() { m_bValid = false; }
 
  private:
+  bool m_bValid = true;
+  CFWL_Widget* const m_pListener;
   std::set<CFWL_Widget*> m_widgets;
-  CFWL_Widget* m_pListener;
-  bool m_bValid;
 };
 
 #endif  // XFA_FWL_CFWL_EVENTTARGET_H_