Fix createSuper in Babel <7.5.5 (#11341)

* Fix createSuper in Babel <7.5.5

In Babel <7.5.5, addHelper only throws when called for the first time.
This was fixed by #10208, but since we are already adding
a workaround for <7.9.0, we may as well fix <7.5.5

* Use 7.0.0 in "babel-old-version" test

packages/babel-plugin-transform-classes/src/inline-createSuper-helpers.js

@@ -3,18 +3,18 @@ import { template, types as t } from "@babel/core";
 const helperIDs = new WeakMap();
 
 export default function addCreateSuperHelper(file) {
-  try {
-    return file.addHelper("createSuper");
-  } catch {
-    // Babel <7.9.0 doesn't support the helper.
-  }
-
   if (helperIDs.has(file)) {
     // TODO: Only use t.cloneNode in Babel 8
     // t.cloneNode isn't supported in every version
     return (t.cloneNode || t.clone)(helperIDs.get(file));
   }
 
+  try {
+    return file.addHelper("createSuper");
+  } catch {
+    // Babel <7.9.0 doesn't support the helper.
+  }
+
   const id = file.scope.generateUidIdentifier("createSuper");
   helperIDs.set(file, id);
 

scripts/integration-tests/e2e-babel-old-version.sh

@@ -23,15 +23,12 @@ cd ../..
 startLocalRegistry "$PWD"/scripts/integration-tests/verdaccio-config.yml
 yarn upgrade --scope @babel
 
-# We use @babel/core 7.5.5 instead of 7.0.0 because without babel/babel#10208
-# our @babel/standalone build fails.
-
 node -e "\
   var pkg = require('./package.json');\
-  pkg.devDependencies['@babel/core'] = '7.5.5';\
+  pkg.devDependencies['@babel/core'] = '7.0.0';\
   Object.assign(pkg.resolutions, {\
-    '@babel/core': '7.5.5',\
-    '@babel/helpers': '7.5.5',\
+    '@babel/core': '7.0.0',\
+    '@babel/helpers': '7.0.0',\
     '@babel/traverse': '7.0.0'\
   });\
   fs.writeFileSync('./package.json', JSON.stringify(pkg, null, 2));\