Fix UNSET problem for text alignment change

Summary: Use UNSET(-1) as default will lead wrong calculation for text alignment. Change it to Gravity.NO_GRAVITY to fix this problem.

Reviewed By: fkgozali

Differential Revision: D3624417

fbshipit-source-id: c116560e64600be60b2fe719f575701b00f20a97

Author: MengjueW

ReactAndroid/src/main/java/com/facebook/react/views/text/ReactTextShadowNode.java

@@ -310,7 +310,7 @@ private static int parseNumericFontWeight(String fontWeightString) {
 
   protected int mNumberOfLines = UNSET;
   protected int mFontSize = UNSET;
-  protected int mTextAlign = UNSET;
+  protected int mTextAlign = Gravity.NO_GRAVITY;
 
   private float mTextShadowOffsetDx = 0;
   private float mTextShadowOffsetDy = 0;