[ember] refactor @ember/polyfills types into their own package (#28797)

* [ember] refactor @ember/polyfills into its own module
fixes https://github.com/typed-ember/ember-cli-typescript/issues/273

* [ember] delay activation of some tests until after future improvements to Ember.assign/merge

types/ember__polyfills/ember__polyfills-tests.ts

@@ -0,0 +1,25 @@
+import { assign, merge } from '@ember/polyfills';
+
+(() => { /* assign */
+    assign({}, { a: 'b'});
+    assign({}, { a: 'b'}).a; // $ExpectType string
+    assign({ a: 6 }, { a: 'b'}).a; // $ExpectType string
+    assign({ a: 6 }, {}).a; // $ExpectType number
+    assign({ b: 6 }, {}).a; // $ExpectError
+    // TODO enable after https://github.com/typed-ember/ember-cli-typescript/issues/291
+    // assign({}, { b: 6 }, {}).b; // $ExpectType number
+    assign({ a: 'hello' }, { b: 6 }, {}).a; // $ExpectType string
+    // TODO enable after https://github.com/typed-ember/ember-cli-typescript/issues/291
+    // assign({ a: 'hello' }, { b: 6 }, { a: true }).a; // $ExpectType boolean
+    // TODO enable after https://github.com/typed-ember/ember-cli-typescript/issues/291
+    // assign({ a: 'hello' }, '', { a: true }).a; // $ExpectError
+    assign({ d: ['gobias industries'] }, { a: 'hello' }, { b: 6 }, { a: true }).d; // $ExpectType string[]
+})();
+
+(() => { /* merge */
+    merge({}, { a: 'b'});
+    merge({}, { a: 'b'}).a; // $ExpectType string
+    merge({ a: 6 }, { a: 'b'}).a; // $ExpectType string
+    merge({ a: 6 }, {}).a; // $ExpectType number
+    merge({ b: 6 }, {}).a; // $ExpectError
+})();

types/ember__polyfills/index.d.ts

@@ -0,0 +1,10 @@
+// Type definitions for @ember/polyfills 3.0
+// Project: http://emberjs.com/
+// Definitions by: Mike North <https://github.com/mike-north>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.8
+
+import Ember from 'ember';
+
+export const assign: typeof Ember.assign;
+export const merge: typeof Ember.merge;

types/ember__polyfills/tsconfig.json

@@ -0,0 +1,28 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "target": "es5",
+        "lib": [
+            "es6",
+            "dom"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "paths": {
+            "@ember/polyfills": ["ember__polyfills"]
+        },
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "ember__polyfills-tests.ts"
+    ]
+}

types/ember__polyfills/tslint.json

@@ -0,0 +1,4 @@
+{
+    "extends": "dtslint/dt.json",
+    "rules": {}
+}