Avoid passing nullptr to vswprintf() inside WideString::FormatV() am: 64d8c24a9f am: eb8a870d5e am: 8ab10fa89f

Original change: https://android-review.googlesource.com/c/platform/external/pdfium/+/2548790

Change-Id: I26e7d03452c05f5669d5f5de619761c78a9b78a0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

core/fxcrt/widestring.cpp

diff --git a/core/fxcrt/widestring.cpp b/core/fxcrt/widestring.cpp
index 10a31c3..4e51a85 100644
--- a/core/fxcrt/widestring.cpp
+++ b/core/fxcrt/widestring.cpp
@@ -287,18 +287,13 @@
 WideString WideString::FormatV(const wchar_t* format, va_list argList) {
   va_list argListCopy;
   va_copy(argListCopy, argList);
-  int maxLen = vswprintf(nullptr, 0, format, argListCopy);
+  auto guess = GuessSizeForVSWPrintf(format, argListCopy);
   va_end(argListCopy);
 
-  if (maxLen <= 0) {
-    va_copy(argListCopy, argList);
-    auto guess = GuessSizeForVSWPrintf(format, argListCopy);
-    va_end(argListCopy);
-
-    if (!guess.has_value())
-      return WideString();
-    maxLen = pdfium::base::checked_cast<int>(guess.value());
+  if (!guess.has_value()) {
+    return WideString();
   }
+  int maxLen = pdfium::base::checked_cast<int>(guess.value());
 
   while (maxLen < 32 * 1024) {
     va_copy(argListCopy, argList);