Fix super handling

packages/babel-plugin-transform-exponentiation-operator/src/index.ts

@@ -14,7 +14,9 @@ export default declare(api => {
   }
 
   function maybeMemoize(node: t.Expression, scope: Scope) {
-    if (scope.isPure(node)) return { assign: node, ref: t.cloneNode(node) };
+    if (scope.isPure(node) || t.isSuper(node)) {
+      return { assign: node, ref: t.cloneNode(node) };
+    }
 
     const id = scope.generateUidIdentifierBasedOnNode(node);
     scope.push({ id });

packages/babel-plugin-transform-exponentiation-operator/test/fixtures/regression/4349-keep-super/input.js

@@ -0,0 +1,5 @@
+foo = {
+  bar() {
+    return super.baz **= 12;
+  }
+}

packages/babel-plugin-transform-exponentiation-operator/test/fixtures/regression/4349-keep-super/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-exponentiation-operator"]
+}

packages/babel-plugin-transform-exponentiation-operator/test/fixtures/regression/4349-keep-super/output.js

@@ -0,0 +1,5 @@
+foo = {
+  bar() {
+    return super.baz = Math.pow(super.baz, 12);
+  }
+};