Roll back workaround for upcoming libc++ bug which has since been fixed upstream.

PiperOrigin-RevId: 640479545
Change-Id: I8a3700ef0b52f5364dcd0903aba196293a96c220

src/xml/xml_util.cc

@@ -481,16 +481,6 @@ bool mjXUtil::ReadAttrValues(XMLElement* elem, const char* attr,
   // read numbers
   for (int i = 0; (max < 0 || i < max) && !strm.eof(); ++i) {
     strm >> token;
-
-    // some C++ libraries do not allow .x instead of 0.x
-    if (!token.empty()) {
-      if (token[0] == std::string(".")[0]) {
-        token = "0" + token;
-      } else if (token[0] == std::string("-")[0] && token[1] == std::string(".")[0]) {
-        token.insert(1, "0");
-      }
-    }
-
     std::istringstream token_strm(token);
     token_strm >> item;
     if (token_strm.fail() || !token_strm.eof()) {