Transform class static block (#12143)

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com>
Co-authored-by: Brian Ng <bng412@gmail.com>

packages/babel-helper-module-transforms/package.json

@@ -21,6 +21,7 @@
     "@babel/helper-split-export-declaration": "workspace:^7.11.0",
     "@babel/helper-validator-identifier": "workspace:^7.10.4",
     "@babel/template": "workspace:^7.10.4",
+    "@babel/traverse": "workspace:^7.11.5",
     "@babel/types": "workspace:^7.11.0",
     "lodash": "^4.17.19"
   }

packages/babel-helper-module-transforms/src/rewrite-this.js

@@ -1,25 +1,21 @@
-import { skipAllButComputedKey } from "@babel/helper-replace-supers";
+import { environmentVisitor } from "@babel/helper-replace-supers";
+import traverse from "@babel/traverse";
+import * as t from "@babel/types";
+
 export default function rewriteThis(programPath: NodePath) {
   // Rewrite "this" to be "undefined".
-  programPath.traverse(rewriteThisVisitor);
+  traverse(programPath.node, { ...rewriteThisVisitor, noScope: true });
 }
 
 /**
  * A visitor to walk the tree, rewriting all `this` references in the top-level scope to be
- * `undefined`.
+ * `void 0` (undefined).
  */
-const rewriteThisVisitor = {
-  ThisExpression(path) {
-    path.replaceWith(path.scope.buildUndefinedNode());
+const rewriteThisVisitor = traverse.visitors.merge([
+  environmentVisitor,
+  {
+    ThisExpression(path) {
+      path.replaceWith(t.unaryExpression("void", t.numericLiteral(0), true));
+    },
   },
-  Function(path) {
-    if (path.isMethod()) skipAllButComputedKey(path);
-    else if (!path.isArrowFunctionExpression()) path.skip();
-  },
-  ClassProperty(path) {
-    skipAllButComputedKey(path);
-  },
-  ClassPrivateProperty(path) {
-    path.skip();
-  },
-};
+]);