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.
constructor({
    textContent,
    textContentStream,
    container,
    viewport,
    textDivs,
    textContentItemsStr,
    enhanceTextSelection,
  }) {
    this._textContent = textContent;
    this._textContentStream = textContentStream;
    this._container = container;
    this._document = container.ownerDocument;
    this._viewport = viewport;
    this._textDivs = textDivs || [];
    this._textContentItemsStr = textContentItemsStr || [];
    this._enhanceTextSelection = !!enhanceTextSelection;
    this._fontInspectorEnabled = !!globalThis.FontInspector?.enabled;
    this._reader = null;
    this._layoutTextLastFontSize = null;
    this._layoutTextLastFontFamily = null;
    this._layoutTextCtx = null;