Split apart the remainder of fpdf_render_render.cpp into per-class files.

core/include/fpdfapi/fpdf_objects.h

Index: core/include/fpdfapi/fpdf_objects.h
diff --git a/core/include/fpdfapi/fpdf_objects.h b/core/include/fpdfapi/fpdf_objects.h
index a6fa056e139c8382e55fb6ce96588fb2566dde43..42282a1dcc24f2ea62f08e3f3202d3090ede8227 100644
--- a/core/include/fpdfapi/fpdf_objects.h
+++ b/core/include/fpdfapi/fpdf_objects.h
@@ -333,6 +333,7 @@ class CPDF_Dictionary : public CPDF_Object {
   }
 
   FX_BOOL KeyExist(const CFX_ByteStringC& key) const;
+  bool IsSignatureDict() const;
 
   // Set* functions invalidate iterators for the element with the key |key|.
   void SetAt(const CFX_ByteStringC& key, CPDF_Object* pObj);