@babel/parser(ts): exported abstract interface is parsed as a class

[armano2]

Bug Report

Current Behavior
Exported abstract interface is parsed by babel/parser as a class, this is only a case when its exported

Input Code

export abstract interface I {}

{
	"type": "ExportNamedDeclaration",
	"specifiers": [],
	"source": null,
	"declaration": {
		"type": "ClassDeclaration",
		"abstract": true,
		"id": {
			"type": "Identifier",
			"identifierName": "I"
		},
		"name": "I"
	},
	"superClass": null,
	"body": {
		"type": "ClassBody",
		"body": []
	}
}

Expected behavior/code
I expect error that abstract keyword is not allowed.

Babel Configuration (.babelrc, package.json, cli command)

  const babel = require('@babel/parser');
  const plugins: ParserPlugin[] = [
    'typescript',
    'objectRestSpread',
    'decorators-legacy',
    'classProperties',
    'asyncGenerators',
    'dynamicImport',
    'estree',
    'bigInt',
    'importMeta'
  ];
  if (jsx) {
    plugins.push('jsx');
  }

  return babel.parse(text, {
    sourceType: 'unambiguous',
    allowImportExportEverywhere: true,
    allowReturnOutsideFunction: true,
    ranges: true,
    plugins
  });

Additional context/Screenshots

• astexplorer
• babeljs playground

)Environment

• Babel version(s): 7.2.3
• Node/npm version: 6-11
• OS: ----
• Monorepo: ---
• How you are using Babel: @babel/parser -> parse

[babel-bot]

Hey @armano2! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
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[armano2]

looks like issue is more serious, abstract is parsed incorrectly:

export abstract foo Bar {}

will be parsed to ClassDeclaration, and same part of code is affecting #9305

{
  "type": "File",
  "program": {
    "type": "Program",
    "sourceType": "module",
    "interpreter": null,
    "body": [
      {
        "type": "ExportNamedDeclaration",
        "specifiers": [],
        "source": null,
        "declaration": {
          "type": "ClassDeclaration",
          "abstract": true,
          "id": {
            "type": "Identifier",
            "name": "Bar"
          },
          "superClass": null,
          "body": {
            "type": "ClassBody",
            "body": []
          }
        }
      }
    ],
    "directives": []
  },
  "comments": []
}

[armano2]

in case of export

https://github.com/babel/babel/blob/master/packages/babel-parser/src/plugins/typescript.js#L1265

        case "abstract":
          if (next || this.match(tt._class)) {
            const cls: N.ClassDeclaration = node;
            cls.abstract = true;
            if (next) this.next();
            return this.parseClass(
              cls,
              /* isStatement */ true,
              /* optionalId */ false,
            );
          }
          break;

next is set to true, and there is no check for keyword anywhere if (next) this.next();