Parsing error on async* generator in object expressions

[RichardHoOoOo]

Take the following code as an example

source  = "const obj = { async* generator() {}};"
esprima.parseScript(source, { tolerant: true }))
code = escodegen.generate(ast);
console.log(code);

The output is:

const obj = {
    async,
    *generator() {
    }
};