message: Allow overriding of theme variable with explicit styles prop on Tab component.
  Fix based on issue
diff: @@ -71,8 +71,8 @@ const DefaultTabBar = createReactClass({
  >
  <Text
  style={[
  - isTabActive ? activeTextStyle : textStyle,
  - { fontSize: tabFontSize }
  + { fontSize: tabFontSize },
  + isTabActive ? activeTextStyle : textStyle
  ]}
  >
  {name}
  