shlwapi: Avoid potential NULL pointer access if HeapAlloc fails.

dlls/shlwapi/istream.c

@@ -364,12 +364,11 @@ static const IStreamVtbl SHLWAPI_fsVTable =
  */
 static IStream *IStream_Create(LPCWSTR lpszPath, HANDLE hFile, DWORD dwMode)
 {
- ISHFileStream* fileStream;
+    ISHFileStream *fileStream;
 
     fileStream = HeapAlloc(GetProcessHeap(), 0, sizeof(ISHFileStream));
+    if (!fileStream) return NULL;
 
- if (fileStream)
- {
     fileStream->IStream_iface.lpVtbl = &SHLWAPI_fsVTable;
     fileStream->ref = 1;
     fileStream->hFile = hFile;
@@ -377,7 +376,7 @@ static IStream *IStream_Create(LPCWSTR lpszPath, HANDLE hFile, DWORD dwMode)
     fileStream->lpszPath = StrDupW(lpszPath);
     fileStream->type = 0; /* FIXME */
     fileStream->grfStateBits = 0; /* FIXME */
- }
+
     TRACE ("Returning %p\n", fileStream);
     return &fileStream->IStream_iface;
 }