This is a Babel 6 plugin to enable extending builtin types like "Error" and "Array" and such, which require special treatment and require static analysis to detect.

In your Babel 6 configuration, for example in a .babelrc you might have

{
 "plugins": [
 ["babel-plugin-transform-builtin-extend", {
 globals: ["Error", "Array"]
 }]
 ]
}

which would enable the plugin and configure it to look for any class extending Error or Array globals.

On older browsers that do not support reassigning the prototype of an existing object, you will need to enable the approximate mode, which will fall back to the Babel 5 behavior of using simple ES5 inheritance to approximate extending a class, though your results may vary depending on your goals.

{
 "plugins": [
 ["babel-plugin-transform-builtin-extend", {
 globals: ["Error", "Array"],
 approximate: true
 }]
 ]
}

This plugin will only reles on assigning __proto__ for static property inheritance from parent constructors. If you are relying on this, it will not work on IE<=10 and any other browsers that don't support __proto__.