Do not retrieve the number of contours for empty glyphs

Before this change php-font-lib always read the number of contours for a glyph. If a glyph has no data the read information would be incorrect. This could lead to invalid parsing of the glyph since the data may not represent the actual glyph format (simple). In fact, the data could be from outside the glyf table entirely. If the glyph was positioned as the last byte in the font a read error would be thrown.

Author: bsweeney

src/FontLib/Glyph/Outline.php

@@ -48,7 +48,7 @@ class Outline extends BinaryStream {
   static function init(glyf $table, $offset, $size, BinaryStream $font) {
     $font->seek($offset);
 
-    if ($font->readInt16() > -1) {
+    if ($size === 0 || $font->readInt16() > -1) {
       /** @var OutlineSimple $glyph */
       $glyph = new OutlineSimple($table, $offset, $size);
     }