allow zero offset when shadow radius is nonzero

Summary:
update creation logic for text shadow: allow shadows with zero offset when the radius is nonzero

(?should we also add a check to drop the node as a no-op when color.alpha == 0 ?)

Reviewed By: yungsters

Differential Revision: D10017778

fbshipit-source-id: 0168ac6db5ad22a5d7eb32dcd184aede361d6651

Author: Timothy Kukulski

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

@@ -6,6 +6,7 @@
  */
 package com.facebook.react.views.text;
 
+import android.graphics.Color;
 import android.graphics.Typeface;
 import android.os.Build;
 import android.text.Layout;
@@ -148,7 +149,10 @@ private static void buildSpannedFromShadowNode(
       if (textShadowNode.mIsLineThroughTextDecorationSet) {
         ops.add(new SetSpanOperation(start, end, new StrikethroughSpan()));
       }
-      if (textShadowNode.mTextShadowOffsetDx != 0 || textShadowNode.mTextShadowOffsetDy != 0) {
+      if ((textShadowNode.mTextShadowOffsetDx != 0
+        || textShadowNode.mTextShadowOffsetDy != 0
+        || textShadowNode.mTextShadowRadius != 0)
+        && Color.alpha(textShadowNode.mTextShadowColor) != 0) {
         ops.add(
             new SetSpanOperation(
                 start,