firefox/profile.js
function mixin(a, b) {
  Object.keys(b).forEach(function(key) {
    a[key] = b[key];
  });
}
function mixin(a, b) {
  Object.keys(b).forEach(function(key) {
    a[key] = b[key];
  });
}
function mixin ( a , b ) { Object . keys ( b ) . forEach ( function ( key ) { a [ key ] = b [ key ] ; } ) ; }
Copies the properties of one object into another.
@param {!Object} a The destination object.
@param {!Object} b The source object to apply as a mixin.
Copies the properties of one object into another .