obj.await should not throw error.

[mysticatea]

From eslint/eslint#5564
On v3.1.1.

In obj.await case, await should not throw a syntax error because this await is IdentifierName (a reserved word is allowed).
Acorn has succeeded to parse it.
I guess this error caused by this line.

"use strict";

const espree = require("espree");
const ast = espree.parse(
    `obj.await`,
    {
        ecmaVersion: 6,
        sourceType: "module"
    }
);

console.log(JSON.stringify(ast, null, 4));

SyntaxError: Unexpected token await
    at Parser.instance.raise.instance.raiseRecoverable (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\espree\espree.js:394:19)
    at Parser.instance.unexpected (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\espree\espree.js:427:14)
    at Parser.esprimaFinishNode (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\espree\espree.js:142:14)
    at Parser.finishNode (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\espree\espree.js:232:34)
    at Parser.pp.parseIdent (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\acorn\dist\acorn.js:678:15)
    at Parser.pp.parseSubscripts (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\acorn\dist\acorn.js:236:28)
    at Parser.pp.parseExprSubscripts (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\acorn\dist\acorn.js:228:15)
    at Parser.pp.parseMaybeUnary (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\acorn\dist\acorn.js:204:17)
    at Parser.pp.parseExprOps (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\acorn\dist\acorn.js:151:19)
    at Parser.pp.parseMaybeConditional (C:\Users\t-nagashima.AD\Documents\GitHub\eslint\node_modules\acorn\dist\acorn.js:133:19)

[nzakas]

I think you're right. I did this initially because Acorn wasn't properly handling await as a reserved word in modules. Maybe it's OK now.

[xjamundx]

I may be able to look at this this week assuming it's removing that check and just making sure the tests don't break

[nzakas]

Should be

[nzakas]

I'm in here looking at other changes, so I'm going to take a look at this while I have the hood up.