Prevent font comparison from throwing NPE.

By mistake we didn't check that family font name exists.

DEVSIX-3389

Autoported commit.
Original commit hash: [7797df7e1]

Author: ars18wrw

itext/itext.layout/itext/layout/font/FontSelector.cs

@@ -193,9 +193,9 @@ private static int CharacteristicsSimilarity(String fontFamily, FontCharacterist
                 }
                 if (!fontFamilySetByCharacteristics) {
                     // if alias is set, fontInfo's descriptor should not be checked
-                    if (!"".Equals(fontFamily) && (null == fontInfo.GetAlias() && fontInfo.GetDescriptor().GetFamilyNameLowerCase
-                        ().Equals(fontFamily) || (null != fontInfo.GetAlias() && fontInfo.GetAlias().ToLowerInvariant().Equals
-                        (fontFamily)))) {
+                    if (!"".Equals(fontFamily) && (null == fontInfo.GetAlias() && null != fontInfo.GetDescriptor().GetFamilyNameLowerCase
+                        () && fontInfo.GetDescriptor().GetFamilyNameLowerCase().Equals(fontFamily) || (null != fontInfo.GetAlias
+                        () && fontInfo.GetAlias().ToLowerInvariant().Equals(fontFamily)))) {
                         score += FONT_FAMILY_EQUALS_AWARD;
                     }
                     else {

port-hash

@@ -1 +1 @@
-96b8bfb82523ec28793f64d5aeb23807247c6b45 
+7797df7e117620e8aa59c17afe07566ab8487f60