[relay-runtime] Unfreeze JSON object to allow reassignment

[dbslone]

Fixes #2049

The issue described in #2049 arises because the object being passed to recycleNodesInto is a frozen object. So nextObject[key] = nextValue will always fail.

This fix currently causes one of tests in packages/react-relay/classic/legacy/store/__tests__/recycleNodesInto-test.js to fail because it uses === comparison but the returned result is the same. Not sure if these tests are still being used since they don't appear to be included when running npm test from the root directory.

[leebyron]

cc @kassens @josephsavona - can you help review this one? Looks like a real issue in Relay attempting to mutate a frozen record, however we should get a gut-check on whether this is the right fix.

[dbslone]

@leebyron @kassens @josephsavona any updates on if this best strategy to resolve this issue?

[josephsavona]

Is this still an issue on master? This has come up previously and we've already made several fixes to recycleNodesInto in order to avoid ending up mutating the previous input exactly because it could be frozen. I'm also concerned about the performance implications of this implementation - at a glance it would seem to incur quite a bit of copying items/properties.

[jardakotesovec]

@josephsavona Just tried with 1.4.1 and also with master and still the same issue.

[mike-marcacci]

I have another fix for this in #2193 which takes a different approach.

[dbslone]

Closing PR in favor of #2192