Fix DCE tests with labels in separate namespace (#225)

* Fix DCE tests with labels in separate namespace

* Convert to do..while loop

packages/babel-plugin-minify-dead-code-elimination/src/index.js

@@ -895,7 +895,13 @@ module.exports = ({ types: t, traverse }) => {
         // here we handle the break labels
         // if they are outside switch, we bail out
         // if they are within the case, we keep them
-        const _isAncestor = isAncestor(path.scope.getBinding(label.node.name).path, path);
+        let labelPath;
+        if (path.scope.getLabel) {
+          labelPath = getLabel(label.node.name, path);
+        } else {
+          labelPath = path.scope.getBinding(label.node.name).path;
+        }
+        const _isAncestor = isAncestor(labelPath, path);
 
         return {
           bail: _isAncestor,
@@ -957,4 +963,15 @@ module.exports = ({ types: t, traverse }) => {
     return path.isFunctionDeclaration()
       || path.isVariableDeclaration({ kind: "var" });
   }
+
+  function getLabel(name, _path) {
+    let label, path = _path;
+    do {
+      label = path.scope.getLabel(name);
+      if (label) {
+        return label;
+      }
+    } while (path = path.parentPath);
+    return null;
+  }
 };