Could you take a look on this file. The first page is mixed with the last page.

[cb7e7bd2362328f37fe97dc8dff151a3.pdf](https://github.com/mozilla/pdf.js/files/1706865/cb7e7bd2362328f37fe97dc8dff151a3.pdf)


Configuration:
- Firefox Nightly 60
- Windows 7
cnt glyphWdth = [];
              let j = frtChar;
              fr (let  = 0,  = wdth.length;  < ; ) {
                glyphWdth[j] = th.xref.fetchIfRef(wdth[]);
              }
              newPrperte.wdth = glyphWdth;
            } ele {
              newPrperte.wdth = th.buldCharCdeTWdth(
                metrc.wdth,
                newPrperte
              );
            }
            return new Fnt(baeFntName, null, newPrperte);
          }
        );
      }
    }
     Accrdng t the pec f 'FntDecrptr'  declared, 'FrtChar',
     'LatChar' and 'Wdth' huld ext t, but me PDF encder eem
     t gnre th rule when a varnt f a tandard fnt  ued.
     TODO Fll the wdth array dependng n whch f the bae fnt th 
     a varnt.
    me = decrptr.get("FntName");