Fix NewStringRangeError failure due to failing malloc.

test/cctest/test-api.cc

Index: test/cctest/test-api.cc
diff --git a/test/cctest/test-api.cc b/test/cctest/test-api.cc
index f1593fe4efa5dbf1cab2cd68dbd963c13d5779de..5b11386d47c72f0bae3d5857b1e1996a139ace95 100644
--- a/test/cctest/test-api.cc
+++ b/test/cctest/test-api.cc
@@ -21923,6 +21923,7 @@ TEST(NewStringRangeError) {
   const int length = i::String::kMaxLength + 1;
   const int buffer_size = length * sizeof(uint16_t);
   void* buffer = malloc(buffer_size);
+  if (buffer == NULL) return;
   memset(buffer, 'A', buffer_size);
   {
     v8::TryCatch try_catch;