Re-use object pointers when object is re-used

[KamranAsif]

Trivial case:

const sourceObj = {...};
const source = { prop1: sourceObj, prop2: sourceObj};

const revisionObj = {...};
const revision = { prop1: revisionObj, prop2: revisionObj};

const revised = revise(source, revision);
assert(revised.prop1 === revised.prop2)

Complex case

const foo = {name: 'bar'};
const bar = {name: 'bar'};
const baz = {name: 'baz'};'

const source = { prop1: foo, prop2: bar};
const revision = { prop1: baz, prop2: baz};

const revised = revise(source, revision);
assert(revised.prop1.name === 'baz' && revised.prop2.name === 'baz');
assert(revised.prop1 === revised.prop2); //Is this something we assert?