Summary:
Current default value of ProgressBarAndroid's styleAttr is "Large" which sets the ProgressBar's style to [Widget_ProgressBar_Large](http://developer.android.com/reference/android/R.style.html#Widget_ProgressBar_Large) at native side. But large is not the default style for the native side ProgressBar.
For example, the size of the ProgressBar is 48dip for default style, but 76dip for large and 16dip for small as in the Material themes. Although the size of ProgressBarAndroid could be set in JS, it'll be better to have the same default style as in native side themes.
My PR adds a "Normal" value for styleAttr prop and makes it the default value.
Closes https://github.com/facebook/react-native/pull/4974
Reviewed By: svcscm
Differential Revision: D2811229
Pulled By: bestander
fb-gh-sync-id: 087f68d1919fe933d86e5194112bf7a5f5b3f3c6
a45219966c