Rework Math.random

[MaxGraey]

For motivation see 1 and 2

[MaxGraey]

@dcodeIO It will be great have inferring return generic types like TS does. In this case after refactoring Math we could get nice random for different types:

export namespace Math {
  export function random<T = f64>(): T {
    // use different implementations for different types of T
    ...
    return result as T;
  }
}

let rnd1 = Math.random();        // infer as Math.random<f64>()
let rnd2: u32 = Math.random();   // infer as Math.random<u32>()
let rnd3 = Math.random() as u64; // infer as Math.random<u64>()
let rnd4 = Math.random<f32>();   // infer as Math.random<f32>()

Actually this valid typescript

[dcodeIO]

Looks good! Relevant v8 commit: v8/v8@ac66c97#diff-202872834c682708e9294600f73e4d15R114