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.
const currentImgData = objsPool.get(objId);
          expect(currentImgData.width).toEqual(firstImgData.width);
          expect(currentImgData.height).toEqual(firstImgData.height);
          expect(currentImgData.kind).toEqual(firstImgData.kind);
          expect(currentImgData.data instanceof Uint8ClampedArray).toEqual(
            true
          );
          expect(
            currentImgData.data.every((value, index) => {
              return value === firstImgData.data[index];
            })
          ).toEqual(true);
        }
      }
      await loadingTask.destroy();
      firstImgData = null;
    });
  });
  describe("Multiple `getDocument` instances", function () {
    
    
    const pdf1 = buildGetDocumentParams("tracemonkey.pdf");
    
    const pdf2 = buildGetDocumentParams("TAMReview.pdf");
    
    const pdf3 = buildGetDocumentParams("issue6068.pdf");
    const loadingTasks = [];
    
    
    async function renderPDF(filename) {