Fixed issue with measuring text with NaN width

Summary:
Looks like `-[NSLayoutManager ensureLayoutForTextContainer:textContainer]` has a bug that cause infinite loop inside this method
during measuring some special characters AND when specified `width` equals NaN (which is useless anyways).

So, we cover this case in this diff.

Reviewed By: javache

Differential Revision: D5859767

fbshipit-source-id: 58a5910f21f282bf5b82494916b5b02ad72d357f

Libraries/Text/RCTShadowText.m

@@ -220,7 +220,10 @@ - (NSTextStorage *)buildTextStorageForWidth:(CGFloat)width widthMode:(YGMeasureM
   }
 
   textContainer.maximumNumberOfLines = _numberOfLines;
-  textContainer.size = (CGSize){widthMode == YGMeasureModeUndefined ? CGFLOAT_MAX : width, CGFLOAT_MAX};
+  textContainer.size = (CGSize){
+    widthMode == YGMeasureModeUndefined || isnan(width) ? CGFLOAT_MAX : width,
+    CGFLOAT_MAX
+  };
 
   [layoutManager addTextContainer:textContainer];
   [layoutManager ensureLayoutForTextContainer:textContainer];