Incorrect prop expansion when key and value names are equal

[xPaw]

Version

3.0.0-alpha.8

Reproduction link

https://github.com/thelounge/thelounge/blob/52002c3e227bbb3ac568d774ed03c08794ee954b/client/components/ChannelWrapper.vue#L8

Steps to reproduce

<template>
	<div :class="[{active: active}, {thisworks: active}]"></div>
</template>

<script>
export default {
	name: "ChannelWrapper",
	props: {
		active: Boolean,
	},
};
</script>

What is expected?

Compiles to {active: _ctx.active}.

What is actually happening?

Compiling via webpack with vue-loader, produces the following code which is not valid JS:

Module parse failed: Unexpected token (5:27)
File was processed with these loaders:
 * ./node_modules/vue-loader/dist/templateLoader.js
 * ./node_modules/vue-loader/dist/index.js
You may need an additional loader to handle the result of these loaders.

| export function render(_ctx, _cache) {
|   return (_openBlock(), _createBlock("div", {
>     class: [{active: active: _ctx.active}, {thisworks: _ctx.active}]
|   }, null, 2 /* CLASS */))
| }

As you can see it produced {active: active: _ctx.active}

---

Installed packages:

"@vue/compiler-sfc": "3.0.0-alpha.8",
"vue": "3.0.0-alpha.8",
"vue-loader": "16.0.0-alpha.3",
"webpack": "4.42.0",

This works in vue2.