constructor (defaultKeybindings, userKeybindings) {
    this.defaultKeybindings = defaultKeybindings
    this.keybindingList = this._buildUiKeybindingList(defaultKeybindings, userKeybindings)
    this.isDirty = false
  }
ctor

@param {Map<String, String>} defaultKeybindings
@param {Map<String, String>} userKeybindings