[private methods] Define private methods before executing initializers (#9248)

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/before-fields/exec.js

@@ -0,0 +1,16 @@
+class Cl {
+  prop = this.#method(1);
+
+  #priv = this.#method(2);
+
+  #method(x) {
+    return x;
+  }
+
+  getPriv() {
+    return this.#priv;
+  }
+}
+
+expect(new Cl().prop).toBe(1);
+expect(new Cl().getPriv()).toBe(2);

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/before-fields/input.js

@@ -0,0 +1,13 @@
+class Cl {
+  prop = this.#method(1);
+
+  #priv = this.#method(2);
+
+  #method(x) {
+    return x;
+  }
+
+  getPriv() {
+    return this.#priv;
+  }
+}

packages/babel-plugin-proposal-private-methods/test/fixtures/private-method/before-fields/output.js

@@ -0,0 +1,34 @@
+var Cl =
+/*#__PURE__*/
+function () {
+  "use strict";
+
+  function Cl() {
+    babelHelpers.classCallCheck(this, Cl);
+
+    _method.add(this);
+
+    babelHelpers.defineProperty(this, "prop", babelHelpers.classPrivateMethodGet(this, _method, _method2).call(this, 1));
+
+    _priv.set(this, {
+      writable: true,
+      value: babelHelpers.classPrivateMethodGet(this, _method, _method2).call(this, 2)
+    });
+  }
+
+  babelHelpers.createClass(Cl, [{
+    key: "getPriv",
+    value: function getPriv() {
+      return babelHelpers.classPrivateFieldGet(this, _priv);
+    }
+  }]);
+  return Cl;
+}();
+
+var _priv = new WeakMap();
+
+var _method = new WeakSet();
+
+var _method2 = function _method2(x) {
+  return x;
+};