Fixes Travis error reporting

Summary:
Just cherry-picked my commit from facebook#508
Closes facebook/yoga#542

Differential Revision: D5002335

Pulled By: emilsjolander

fbshipit-source-id: 3f61a235c41627e9cfb90dce150323f11892e65f

Author: Maël Nison

ReactCommon/yoga/yoga/Yoga.c

@@ -415,7 +415,7 @@ YGConfigRef YGConfigGetDefault() {
 
 YGConfigRef YGConfigNew(void) {
   const YGConfigRef config = gYGMalloc(sizeof(YGConfig));
-  YGLog(NULL, config != NULL, "Could not allocate memory for config");
+  YGAssert(config != NULL, "Could not allocate memory for config");
 
   gConfigInstanceCount++;
   memcpy(config, &gYGConfigDefaults, sizeof(YGConfig));