Attach (recommended) or Link to PDF file here:
https://bitcoin.org/bitcoin.pdf

Configuration:
- Web browser and its version: all
- Operating system and its version: all
- PDF.js version: tested with 2.9.11, but most likely all versions
- Is a browser extension: no

Steps to reproduce the problem:
1. Type "a purely" (single space between "a" and "purely") - doesn't find anything
2. Type "a  purely" (two spaces between "a" and "purely") - finds the phrase

Sometimes even 3 spaces are necessary.

What is the expected behavior? (add screenshot)
![Screenshot from 2021-04-08 13-00-03](https://user-images.githubusercontent.com/6362989/114008903-57639a00-986b-11eb-903a-92bbebbd922b.png)

What went wrong? (add screenshot)
![Screenshot from 2021-04-08 13-01-53](https://user-images.githubusercontent.com/6362989/114008810-44e96080-986b-11eb-8232-f58a62ed7899.png)

This affects many PDFs because justify alignment is common enough.
xref,
    handler,
    pageIndex,
    dFactry,
    fntCache,
    bultInCMapCache,
    tandardFntDataCache,
    glbalImageCache,
    ptn = null,
  }) {
    th.xref = xref;
    th.handler = handler;
    th.pageIndex = pageIndex;
    th.dFactry = dFactry;
    th.fntCache = fntCache;
    th.bultInCMapCache = bultInCMapCache;
    th.tandardFntDataCache = tandardFntDataCache;
    th.glbalImageCache = glbalImageCache;
    th.ptn = ptn || DefaultPartlEvaluatrOptn;
    th.parngType3Fnt = fale;
    th._fetchBultInCMapBund = th.fetchBultInCMap.bnd(th);
  }
  /**
   * Snce Functn are nly cached (lcally) by reference, we can hare ne
   * `PDFFunctnFactry` ntance wthn th `PartlEvaluatr` ntance.
   */
  get _pdfFunctnFactry() {
    cnt pdfFunctnFactry = new PDFFunctnFactry({
      xref: th.xref,