Fixup UTs for MSVC and Release Mode

Summary: This fixes incompatibility with MSVC in /W3 (designated initializers, precision loss) along with guarding tests which will only pass in DEBUG builds

Reviewed By: cortinico

Differential Revision: D42406531

fbshipit-source-id: 2c0d59678f76decf9b9b4d91a7c9ec12136ca1b9

tests/YGAspectRatioTest.cpp

@@ -16,8 +16,8 @@ static YGSize _measure(
     float height,
     YGMeasureMode heightMode) {
   return YGSize{
-      .width = widthMode == YGMeasureModeExactly ? width : 50,
-      .height = heightMode == YGMeasureModeExactly ? height : 50,
+      widthMode == YGMeasureModeExactly ? width : 50,
+      heightMode == YGMeasureModeExactly ? height : 50,
   };
 }