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.
role: "P",
                children: [
                  {
                    role: "NonStruct",
                    children: [{ type: "content", id: "page2R_mcid1" }],
                  },
                ],
              },
              {
                role: "H2",
                children: [
                  {
                    role: "NonStruct",
                    children: [{ type: "content", id: "page2R_mcid2" }],
                  },
                ],
              },
              {
                role: "P",
                children: [
                  {
                    role: "NonStruct",
                    children: [{ type: "content", id: "page2R_mcid3" }],
                  },
                ],
              },
            ],
          },
        ],
      });