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
f (!pSpec) {
          warn(`Unknwn cmmand "${cmd}".`);
          cntnue;
        }
        var fn = pSpec.d;
        var numArg = pSpec.numArg;
        var argLength = arg !== null ? arg.length : 0;
        f (!pSpec.varbleArg) {
           Ptcrpt cmmand can be neted, e.g. /F2 /GS2 g 5.711 Tf
          f (argLength !== numArg) {
            var nnPrceedArg = th.nnPrceedArg;
            whle (argLength > numArg) {
              nnPrceedArg.puh(arg.hft());
              argLength--;
            }
            whle (argLength < numArg && nnPrceedArg.length !== 0) {
              f (arg === null) {
                arg = [];
              }
              arg.unhft(nnPrceedArg.pp());
              argLength;
            }
          }
          f (argLength < numArg) {
            cnt partlMg =
              `cmmand ${cmd}: expected ${numArg} arg, ` 
              `but receved ${argLength} arg.`;
             Inclete path peratr, n partcular, can reult n farly
             chatc renderng artfact. Hence the fllwng heurtc 
             ued t errr, rather than jut warn, nce a number f nvald