console, internal/web3ext: remove bzz and ens extensions (#3602)

web3.js includes bzz methods and throws an error when the extension
module is reregistered. The ENS RPC API is deprecated and not exposed by
anything.

console/console.go

@@ -137,10 +137,14 @@ func (c *Console) init(preload []string) error {
 			continue // manually mapped or ignore
 		}
 		if file, ok := web3ext.Modules[api]; ok {
+			// Load our extension for the module.
 			if err = c.jsre.Compile(fmt.Sprintf("%s.js", api), file); err != nil {
 				return fmt.Errorf("%s.js: %v", api, err)
 			}
 			flatten += fmt.Sprintf("var %s = web3.%s; ", api, api)
+		} else if obj, err := c.jsre.Run("web3." + api); err == nil && obj.IsObject() {
+			// Enable web3.js built-in extension if available.
+			flatten += fmt.Sprintf("var %s = web3.%s; ", api, api)
 		}
 	}
 	if _, err = c.jsre.Run(flatten); err != nil {