scale(x,0) has unexpected behaviour

[original001]

test case:
var scaled = new Vector(10, 10).scale(1, 0)

expected behaviour
scaled === (10,0)

actual behaviour
scaled === (10,10)

I found out that reason is implicitly type infer in method scale

this['y'] = y || x;

I wanted to make PR, but don't know, how you build your SAT.min.js file

[jriecken]

Thanks, I've fixed it and released 0.7.1 of the sat package.