message: Defaulted large title font size to null
  If titleFontSize={14} for example then don't want this to apply to large title too. This makes font size prop unique because others should apply to both
diff: @@ -8,8 +8,8 @@ import CollapsingBar from './CollapsingBar';
  import TabBar from './TabBar';
  import StatusBar from './StatusBar';
  -var getValue = (prop: string | ((standard: boolean) => string), standard: boolean) => (
  - typeof prop === 'function' ? prop(standard) : prop
  +var getValue = (prop: string | ((standard: boolean) => string), standard: boolean, defaultValue = prop) => (
  + typeof prop === 'function' ? prop(standard) : defaultValue
  )
  class NavigationBar extends React.Component<any, any> {
  @@ -32,7 +32,7 @@ class NavigationBar extends React.Component<any, any> {
  titleFontStyle: getValue(titleFontStyle, true),
  largeTitleFontStyle: getValue(titleFontStyle, false),
  titleFontSize: getValue(titleFontSize, true),
  - largeTitleFontSize: getValue(titleFontSize, false)
  + largeTitleFontSize: getValue(titleFontSize, false, null)
  }
  var childrenArray = (React.Children.toArray(children) as ReactElement<any>[]);
  var statusBar = childrenArray.find(({type}) => type === StatusBar);
  