Unexpected comma in the function declaration

[roman-simionov]

Version

2.6.10

Reproduction link

https://github.com/vuejs/vue/blob/dev/dist/vue.esm.browser.js#L3296

Steps to reproduce

See the link https://github.com/vuejs/vue/blob/dev/dist/vue.esm.browser.js#L3296

What is expected?

function createComponentInstanceForVnode (
vnode, // we know it's MountedComponentVNode but flow doesn't
parent // activeInstance in lifecycle state
) {
...
}

What is actually happening?

function createComponentInstanceForVnode (
vnode, // we know it's MountedComponentVNode but flow doesn't
parent, // activeInstance in lifecycle state
) {
...
}

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I've got an error when trying to add the vue.esm.browser.js file into a bundle using systemjs-builder