Fix large PDF generation on web with compressed xref

 # Changelog
 
+## 3.8.1
+
+- Fix large PDF generation on web with compressed xref
+
 ## 3.8.0
 
 - Update xml dependency range

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import 'dart:math' as math;
 import 'dart:typed_data';
 
 import 'data_types.dart';
@@ -185,11 +186,7 @@ class PdfXrefTable extends PdfDataType {
       params['/Index'] = PdfArray.fromNum(blocks);
     }
 
-    var bytes = 2; // A pdf less than 256 bytes is unlikely
-    while (1 << (bytes * 8) < offset) {
-      bytes++;
-    }
-
+    final bytes = (math.log(offset) ~/ math.ln2) ~/ 8;
     final w = [1, bytes, 1];
     params['/W'] = PdfArray.fromNum(w);
     final wl = w.reduce((a, b) => a + b);

@@ -3,7 +3,7 @@ description: A pdf producer for Dart. It can create pdf files for both web or fl
 homepage: https://github.com/DavBfr/dart_pdf/tree/master/pdf
 repository: https://github.com/DavBfr/dart_pdf
 issue_tracker: https://github.com/DavBfr/dart_pdf/issues
-version: 3.8.0
+version: 3.8.1
 
 environment:
   sdk: ">=2.12.0 <3.0.0"