Attach (recommended) or Link to PDF file here:
http://mariovalle.name/SciViz/1-s2.0-S0097849310001846-main.pdf

Configuration:
- Web browser and its version: Using pdf.js from Node.js through npm package `pdfjs-dist`
- Operating system and its version: Windows 10 64bits
- PDF.js version: 2.6.347
- Is a browser extension: No

Steps to reproduce the problem:
1. Load the file in acrobat
2. In document properties look at the Author field: it is `Samuel Silva; Beatriz Sousa Santos; Joaquim Madeira`
3. Look at  Additional metadata > advanced > dc:creator. It is marked as `seq container` and contains the 3 authors.
4. Using the code below gives: `"Author": "Samuel Silva"` that is, only the first one. And `"dc:creator": "Samuel SilvaBeatriz Sousa SantosJoaquim Madeira"`, that is the three authors squashed together without separators.

What is the expected behavior? (add screenshot)
In both fields the three authors as a single string with some sort of separator between them. Note that other pdf files that contains multiple authors already have them as a single string with names separated by commas.

The code used:
```
var pdfjsLib = require("pdfjs-dist/es5/build/pdf.js");
var pdfPath = "http://mariovalle.name/SciViz/1-s2.0-S0097849310001846-main.pdf";
var loadingTask = pdfjsLib.getDocument(pdfPath);
loadingTask.promise
  .then(function (doc) {
    var lastPromise;
    lastPromise = doc.getMetadata().then(function (data) {
      console.log(JSON.stringify(data.info, null, 2));
      if (data.metadata) {
        console.log(JSON.stringify(data.metadata.getAll(), null, 2));
      }
    });
  });
```
expect(metadata.has("dc:title")).toBeTruthy();
    expect(metadata.has("dc:qux")).toBeFalsy();
    expect(metadata.get("dc:title")).toEqual("'Foo bar baz'");
    expect(metadata.get("dc:qux")).toEqual(null);
    expect(metadata.getAll()).toEqual({ "dc:title": "'Foo bar baz'" });
  });
  it("should gracefully handle unbalanced end tags (issue 10410)", function () {
    const data =
      '<?xpacket begin="Ã¯Â»Â¿" id="W5M0MpCehiHzreSzNTczkc9d"?>' +
      '<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">' +
      '<rdf:Description rdf:about="" ' +
      'xmlns:pdf="http://ns.adobe.com/pdf/1.3/">' +
      "<pdf:Producer>Soda PDF 5</pdf:Producer></rdf:Description>" +
      '<rdf:Description rdf:about="" ' +
      'xmlns:xap="http://ns.adobe.com/xap/1.0/">' +
      "<xap:CreateDate>2018-10-02T08:14:49-05:00</xap:CreateDate>" +
      "<xap:CreatorTool>Soda PDF 5</xap:CreatorTool>" +
      "<xap:MetadataDate>2018-10-02T08:14:49-05:00</xap:MetadataDate> " +
      "<xap:ModifyDate>2018-10-02T08:14:49-05:00</xap:ModifyDate>" +
      '</rdf:Description><rdf:Description rdf:about="" ' +
      'xmlns:xmpMM="http://ns.adobe.com/xap/1.0/mm/">' +
      "<xmpMM:DocumentID>uuid:00000000-1c84-3cf9-89ba-bef0e729c831" +
      "</xmpMM:DocumentID></rdf:Description>" +
      '</rdf:RDF></x:xmpmeta><?xpacket end="w"?>';
    const metadata = new Metadata(data);
    expect(isEmptyObj(metadata.getAll())).toEqual(true);
  });
  it("should not be vulnerable to the billion laughs attack", function () {
    const data =
      '<?xml version="1.0"?>' +