A class for managing the editor toolbar. Acts as a bridge between a {@link goog.editor.Field} and a {@link goog.ui.Toolbar}. The {@code toolbar} argument must be an instance of {@link goog.ui.Toolbar} or a subclass. This class doesn't care how the toolbar was created. As long as one or more controls hosted in the toolbar have IDs that match built-in {@link goog.editor.Command}s, they will function as expected. It is the caller's responsibility to ensure that the toolbar is already rendered or that it decorates an existing element.