Assert: Restore assert.push() without deprecation.

Reverts commit 41383db. It's still used by numerous plugins that
have no other reason to break. It's trivial to map to the new method
and requires no maintenance or increased complexity, and we're not
under any size constraints. Let's keep it around.

Author: Krinkle

docs/api/assert/push.md

@@ -4,14 +4,12 @@ title: assert.push()
 excerpt: Report the result of a custom assertion.
 groups:
   - deprecated
-  - removed
 redirect_from:
   - "/config/QUnit.push/"
   - "/extension/QUnit.push/"
   - "/api/extension/QUnit.push/"
 version_added: "1.0.0"
 version_deprecated: "2.1.1"
-version_removed: "unreleased"
 ---
 
 `push( result, actual, expected, message )`
@@ -35,7 +33,6 @@ To safely report a global error from inside a plugin or other integration layer,
 
 ## Changelog
 
-| UNRELEASED | Removed.
 | [QUnit 2.1.0](https://github.com/qunitjs/qunit/releases/tag/2.1.0) | Deprecated. Use `assert.pushResult` instead.
 | [QUnit 2.0.0](https://github.com/qunitjs/qunit/releases/tag/2.0.0)| Remove `QUnit.push` alias.
 | [QUnit 1.15.0](https://github.com/qunitjs/qunit/releases/tag/1.15.0) | Rename `QUnit.push` to `QUnit.assert.push`, with alias.

src/assert.js

@@ -81,6 +81,17 @@ class Assert {
     });
   }
 
+  push (result, actual, expected, message, negative) {
+    const currentAssert = this instanceof Assert ? this : config.current.assert;
+    return currentAssert.pushResult({
+      result,
+      actual,
+      expected,
+      message,
+      negative
+    });
+  }
+
   // Public API to internal test.pushResult()
   pushResult (resultInfo) {
     // Destructure of resultInfo = { result, actual, expected, message, negative }