P2 Config Seems strange

[englercj]

this line in the ctor of the P2 World seems wrong:

https://github.com/photonstorm/phaser/blob/master/src/physics/p2/World.js#L27

if (typeof config === 'undefined' || !config.hasOwnProperty('gravity') || !config.hasOwnProperty('broadphase'))
    {
        config = { gravity: [0, 0], broadphase: new p2.SAPBroadphase() };
    }

Seems like that means if I pass in { gravity: [0, -9] } that my gravity will be overridden since I don't pass a broadphase. Is this intentional?

[pnstickne]

It does seem odd - maybe some historical compatibility issue. But I've go nothing.