Attach (recommended) or Link to PDF file here:
[双引号不正常.pdf](https://github.com/mozilla/pdf.js/files/3533108/default.pdf)


Configuration:
- Web browser and its version:  IE11 , chrome 
- Operating system and its version:  win7
- PDF.js version:  master
- Is a browser extension: nothing 
teps to reproduce the problem:
1. viewer.html web  online preview


What is the expected behavior? (add screenshot)
Displayed in normal characters.

What went wrong? (add screenshot)
![20190823143813](https://user-images.githubusercontent.com/6269307/63571860-062e6600-c5b4-11e9-9fff-75d65cf6bade.png)

Not only the two characters I took screenshots, but also a lot of garbled Chinese punctuation. For example, the Chinese 《》 symbol. But these garbled characters only appear in some specific very old pdf files.

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):nothing 

glyphId = cidToGidMap[cid];
        }
        if (glyphId >= 0 && glyphId < numGlyphs && hasGlyph(glyphId)) {
          charCodeToGlyphId[charCode] = glyphId;
        }
      });
    } else {
      
      
      const cmapTable = readCmapTable(
        tables.cmap,
        font,
        this.isSymbolicFont,
        properties.hasEncoding
      );
      const cmapPlatformId = cmapTable.platformId;
      const cmapEncodingId = cmapTable.encodingId;
      const cmapMappings = cmapTable.mappings;
      const cmapMappingsLength = cmapMappings.length;
      let baseEncoding = [],
        forcePostTable = false;
      if (
        properties.hasEncoding &&
        (properties.baseEncodingName === "MacRomanEncoding" ||
          properties.baseEncodingName === "WinAnsiEncoding")
      ) {
        baseEncoding = getEncoding(properties.baseEncodingName);
      }