Default value expressions in functions have incorrect 'this'

[LPGhatguy]

I'm using this Flow-enhanced JS:

// @flow

class XYZ {
	x = 5;

	show(value: number = this.x) {
		console.log(value);
	}
}

Flow says:

XXX: 	show(value: number = this.x) {
     	                          ^ property `x`. Property cannot be accessed on
XXX: 	show(value: number = this.x) {
     	                     ^^^^ global object

But stripping the types and running this in Chrome works just fine!

class XYZ {
	constructor() {
		this.x = 5;
	}

	show(value = this.x) {
		console.log(value);
	}
}

new XYZ().show(); // 5

In addition, this MDN example seems to note that this should be the function, not the global scope in default parameters.

[danieljuhl]

Duplicate of #1234