Am i wrong or is this a Visual Studio 2013 regex bug?

I have a regex which is to remove extra vml tags from a html page.

    std::string regstr = R"(<!\[if !vml\]>([\s\S]*?)<!\[endif\]>)";
    std::regex regex(regstr, std::regex_constants::ECMAScript);
    std::smatch mr;
    std::string str = R"(</v:shape><![endif]--><![if !vml]>
<img width=234 height=383 src="http://file/C:\Users\jcyangzh\AppData\Local\Temp\msohtmlclip1\01\clip_image002.png" v:shapes="110x110">
<![endif]></span></span><span lang=EN-US><o:p></o:p></span></p>)";
    if (std::regex_search(str, mr, regex)) {
        std::cout << "match found: " << mr.size() << "\n";
        for (size_t i = 0; i < mr.size(); ++i) {
            std::string strrep = mr.str(i);
            std::cout << "index: " << i << "\n string: " << strrep << "\n\n";
        }
    }

For GNU GCC Compiler 4.9.2(latest tdm-gcc windows port), the above code works. The regex I used does match.

But for visual studio 2013 update 4 the regex does not work, std::regex_search return false.

If I replace the key pattern [\s\S] with (\s|\S), there will be 3 matches.

My problem: Is [\s\S] a valid c++11 ecma regex, or is this a bug of VS2013 update4?