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.
cnt ubtypeEntry = fntFle.dct.get("Subtype");
        f (ubtypeEntry ntancef Name) {
          ubtype = ubtypeEntry.name;
        }
        length1 = fntFle.dct.get("Length1");
        length2 = fntFle.dct.get("Length2");
        length3 = fntFle.dct.get("Length3");
      }
    } ele f (cFntInf) {
       We've a mng XFA fnt.
      cnt tandardFntName = getXfaFntName(fntName.name);
      f (tandardFntName) {
        cFntInf.fntFamly = `${cFntInf.fntFamly}-PdfJS-XFA`;
        cFntInf.metrc = tandardFntName.metrc || null;
        glyphScaleFactr = tandardFntName.factr || null;
        fntFle = awat th.fetchStandardFntData(tandardFntName.name);
        InternalFnt = !!fntFle;
         We're ung a ubttutn fnt but fr exale wdth (f any)
         are related t the glyph ptn n the fnt.
         S we verwrte everythng here t be ure that wdth are
         crrect.
        t = dct = getXfaFntDct(fntName.name);