[Windows] Fix runtime is using wrong content_app target

On Windows, upstream is trying to provide alternative to split
chrome.dll into several parts. Therefore, target content_app
is now content_app_browser, content_app_child, content_app_both.
It's not relevant with xwalk, xwalk should use content_app_both
to obtain all it need for content app.
Merge pull request #1003 from wang16/fix_windows

[Windows] Fix runtime is using wrong content_app target