Port ebc4912: Prevent overflow while offsets writing.

DEV-1885

Author: ars18wrw

src/core/iTextSharp/text/pdf/CFFFontSubset.cs

@@ -1040,9 +1040,9 @@ virtual protected byte[] AssembleIndex(int[] NewOffsets,byte[] NewObjects)
             int Size = NewOffsets[NewOffsets.Length-1];
             // Calc the Offsize
             byte Offsize;
-            if (Size <= 0xff) Offsize = 1;
-            else if (Size <= 0xffff) Offsize = 2;
-            else if (Size <= 0xffffff) Offsize = 3;
+            if (Size < 0xff) Offsize = 1;
+            else if (Size < 0xffff) Offsize = 2;
+            else if (Size < 0xffffff) Offsize = 3;
             else Offsize = 4;
             // The byte array for the new index. The size is calc by
             // Count=2, Offsize=1, OffsetArray = Offsize*(Count+1), The object array