RFC: Deprecate Ember.assign

text/0750-deprecate-ember-assign.md

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+---
+Stage: Accepted
+Start Date: 2021-05-26
+Release Date: Unreleased
+Release Versions:
+  ember-source: vX.Y.Z
+  ember-data: vX.Y.Z
+Relevant Team(s): Ember.js
+RFC PR: https://github.com/emberjs/rfcs/pull/750
+---
+
+<!---
+Directions for above:
+
+Stage: Leave as is
+Start Date: Fill in with today's date, YYYY-MM-DD
+Release Date: Leave as is
+Release Versions: Leave as is
+Relevant Team(s): Fill this in with the [team(s)](README.md#relevant-teams) to which this RFC applies
+RFC PR: Fill this in with the URL for the Proposal RFC PR
+-->
+
+# Deprecate Ember.assign
+
+## Summary
+
+Now that Ember is dropping support for IE11, we no longer need `Ember.assign` as a polyfill since `Object.assign`
+is available in all browsers that Ember v4.x supports ([CanIUse](https://caniuse.com/mdn-javascript_builtins_object_assign), [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#browser_compatibility)).
+
+## Motivation
+
+The polyfill is no longer necessary, as well as being another Emberism that can be removed. Apps and addons can use `Object.assign` or object destructuring depending on their browser support targets.
+
+## Transition Path
+
+The transition path is relatively simple: apps that use Ember 4.x will replace `Ember.assign` with `Object.assign`, and apps and addons that use or support Ember 3.x can continue to use the polyfill if needed.
+
+ex:
+```
+import { assign as emberAssign } from '@ember/polyfills';
+
+const assign = Object.assign || emberAssign;
+```
+
+## How We Teach This
+
+A descriptive deprecation message alerting a developer that `Ember.assign` is deprecated and can be replaced with `Object.assign`.
+
+## Drawbacks
+
+The only drawback is replacing the polyfill assign with the native assign, but there is minimal effort to do this.
+
+## Alternatives
+
+Doing nothing.
+
+## Unresolved questions
+
+None.