Merge pull request #1035 from embroider-build/optimize-ember-cli-babel

Optimize ember-cli-babel handling

packages/compat/src/compat-adapters/ember-cli-babel.ts

@@ -0,0 +1,22 @@
+import writeFile from 'broccoli-file-creator';
+import V1Addon from '../v1-addon';
+
+// Because almost every addon depends on ember-cli-babel, and because ember-cli
+// instantiates a separate instance of Addon per consumer, approximately *half*
+// of all Addon instances in a typical app will be copies of ember-cli-babel.
+//
+// Under embroider, *all* of them should be contributing no files to the build.
+export default class EmberCliBabel extends V1Addon {
+  // this ensures we don't bother smooshing together a large number of useless
+  // copies of the addon.
+  hasAnyTrees() {
+    return false;
+  }
+
+  // and the one copy that we do emit should just be an empty valid package. We
+  // don't want the babel helpers it emits, they're not even used under
+  // Embroider anyway.
+  get v2Tree() {
+    return writeFile('package.json', JSON.stringify(this.newPackageJSON, null, 2));
+  }
+}