squaredDistance function
Calculates the squared euclidian distance between two vec2's
@param {ReadonlyVec2} a the first operand @param {ReadonlyVec2} b the second operand @returns {Number} squared distance between a and b
Implementation
List<double> squaredDistance(a, b) {
var x = b[0] - a[0], y = b[1] - a[1];
return x * x + y * y;
}