Fix <!DOCTYPE> parsing

[m0nzderr]

Consider the following test cases:

var docA=new DOMParser().parseFromString('<!DOCTYPE foo> <foo/>',"text/xml"),
     docB=new DOMParser().parseFromString('<!DOCTYPE foo SYSTEM "bar"> <foo/>',"text/xml"),
     docC=new DOMParser().parseFromString('<!DOCTYPE foo SYSTEM "bar" [<!ENTITY bar "BAR">]> <foo/>',"text/xml"),
    docD=new DOMParser().parseFromString('<!DOCTYPE foo [<!ENTITY bar "BAR">]> <foo>&bar;</foo>',"text/xml");

console.log(docA.doctype);
console.log(docB.doctype);
console.log(docC.doctype);
console.log(docD.doctype);

Current output:

null
null
null
entity not found:&bar;
null

Expected output: (e.g, produced in in Chrome)

<!DOCTYPE foo>
<!DOCTYPE foo SYSTEM "bar">
<!DOCTYPE foo SYSTEM "bar">
<!DOCTYPE foo>

The first one is easy-fixer: doctype field just left blank. One can check that DocumentType node is already there:

docA:

Document {
  doctype: null,
  implementation: { _features: {} },
  childNodes: 
   { '0': 
      DocumentType {
        name: 'foo',
        nodeName: 'foo',
        publicId: false,
        systemId: false,
.....

Next, checking the DocumentType itself, some issues with systemId are apparent. In the both, external and internal DTD cases:

docB:

      DocumentType {
        name: 'foo',
        nodeName: 'foo',
        publicId: false,
        systemId: '>',

docC:

    DocumentType {
        name: 'foo',
        nodeName: 'foo',
        publicId: false,
       systemId: '[',
        lineNumber: 1,

And, finally, some support for dealing with entities would be great. The "options.entityMap" patch might solve the problem provided with some mechanisms for handling parsed DTD definitions.

Thanks.

[codler]

A "options.entityMap" patch would be great! #131