Viewer:  https://mozilla.github.io/pdf.js/web/viewer.html
Chrome on Windows 10
When the attached PDF file is viewed, some of the fonts display as garbled text. 
[Arial, Courier, Times New Roman]
The file views correctly in Adobe Reader.
[fff.pdf](https://github.com/mozilla/pdf.js/files/4652174/fff.pdf)

const glyphProfile = sanitizeGlyph(
          oldGlyfData,
          locaEntries[i].offset,
          locaEntries[i].endOffset,
          newGlyfData,
          writeOffset,
          hintsValid
        );
        const newLength = glyphProfile.length;
        if (newLength === 0) {
          missingGlyphs[i] = true;
        }
        if (glyphProfile.sizeOfInstructions > maxSizeOfInstructions) {
          maxSizeOfInstructions = glyphProfile.sizeOfInstructions;
        }
        writeOffset += newLength;
        itemEncode(locaData, j, writeOffset);
      }
      if (writeOffset === 0) {
        
        
        const simpleGlyph = new Uint8Array([
          0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 49, 0,
        ]);
        for (i = 0, j = itemSize; i < numGlyphsOut; i++, j += itemSize) {
          itemEncode(locaData, j, simpleGlyph.length);
        }
        glyf.data = simpleGlyph;
      } else if (dupFirstEntry) {