OptionalContent: Remove some unnecessary copy()
diff --git a/poppler/OptionalContent.cc b/poppler/OptionalContent.cc
index 75b93f4..7a5db5c 100644
--- a/poppler/OptionalContent.cc
+++ b/poppler/OptionalContent.cc
@@ -194,7 +194,7 @@
   return result;
 }
 
-bool OCGs::evalOCVisibilityExpr(Object *expr, int recursion) {
+bool OCGs::evalOCVisibilityExpr(const Object *expr, int recursion) {
   OptionalContentGroup *ocg;
   bool ret;
 
@@ -217,7 +217,7 @@
   Object op = expr2.arrayGet(0);
   if (op.isName("Not")) {
     if (expr2.arrayGetLength() == 2) {
-      Object obj = expr2.arrayGetNF(1).copy();
+      const Object &obj = expr2.arrayGetNF(1);
       ret = !evalOCVisibilityExpr(&obj, recursion + 1);
     } else {
       error(errSyntaxError, -1,
@@ -227,13 +227,13 @@
   } else if (op.isName("And")) {
     ret = true;
     for (int i = 1; i < expr2.arrayGetLength() && ret; ++i) {
-      Object obj = expr2.arrayGetNF(i).copy();
+      const Object &obj = expr2.arrayGetNF(i);
       ret = evalOCVisibilityExpr(&obj, recursion + 1);
     }
   } else if (op.isName("Or")) {
     ret = false;
     for (int i = 1; i < expr2.arrayGetLength() && !ret; ++i) {
-      Object obj = expr2.arrayGetNF(i).copy();
+      const Object &obj = expr2.arrayGetNF(i);
       ret = evalOCVisibilityExpr(&obj, recursion + 1);
     }
   } else {
diff --git a/poppler/OptionalContent.h b/poppler/OptionalContent.h
index c383262..f9c5260 100644
--- a/poppler/OptionalContent.h
+++ b/poppler/OptionalContent.h
@@ -4,7 +4,7 @@
 //
 // Copyright 2007 Brad Hards <bradh@kde.org>
 // Copyright 2008 Carlos Garcia Campos <carlosgc@gnome.org>
-// Copyright 2013, 2018 Albert Astals Cid <aacid@kde.org>
+// Copyright 2013, 2018, 2019 Albert Astals Cid <aacid@kde.org>
 // Copyright 2018 Adam Reichold <adam.reichold@t-online.de>
 //
 // Released under the GPL (version 2, or later, at your option)
@@ -58,7 +58,7 @@
 private:
   bool ok;
 
-  bool evalOCVisibilityExpr(Object *expr, int recursion);
+  bool evalOCVisibilityExpr(const Object *expr, int recursion);
   bool allOn( Array *ocgArray );
   bool allOff( Array *ocgArray );
   bool anyOn( Array *ocgArray );