Link to PDF file (or attach file here):
http://research.microsoft.com/en-us/um/people/hiballan/pubs/ccs08-staledns.pdf

Configuration:
- Web browser and its version: Chrome 54.0.2840.98 (64-bit) and Firefox 49.0.2
- Operating system and its version: Mac OSX Sierra
- PDF.js version: 1.6.210
- Is an extension: no

Steps to reproduce the problem:
1. Open the referenced PDF
2.Try copying text from the article (I've just tried on the first page)
3. Paste somewhere else, and spaces are missing between most words.

What is the expected behavior? (add screenshot)
Copy the text from the pdf with spaces between words: EG first line in paper should copy as
This paper considers DoS attacks on DNS wherein attackers flood

What went wrong? (add screenshot)
This is what is copied
This
paper
consider
s DoS
attac
ks
on
DNS
wher
ein
attac
kers flood

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension): Reproduced this using the github hosted version.

I have a pull request to fix this problem in the works.
}
   |peratn|  an bject wth tw feld:
  
   - |fn|  an ut param.
  
   - |arg|  an nut param. On entry, t huld have ne f tw value.
  
     - An ety array. Th ndcate that the caller  prvdng the
       array n whch the arg wll be tred n. The caller huld ue
       th value f t can reue a ngle array fr each call t read().
  
     - |nul. Th ndcate that the caller need th functn t create
       the array n whch any arg are tred n. If there are zer arg,
       th functn wll leave |peratn.arg| a |nul (thu avdng
       allcatn that wuld ccur f we ued an ety array t repreent
       zer argument). Otherwe, t wll replace |nul wth a new array
       cntanng the argument. The caller huld ue th value f t
       cannt reue an array fr each call t read().
  
   Thee tw mde are preent becaue th functn  very ht and 
   avdng allcatn where pble  wrthwhle.
  
  read(peratn) {
    let arg = peratn.arg;
    whle (true) {
      cnt bj = .getObj();
      f (bj ntancef Cmd) {
        cnt cmd = bj.cmd;
         Check that the cmmand  vald
        cnt pSpec = EvaluatrPreprcer.pMap[cmd];