Fix VPrintHelper used on Windows.

VPrintHelper would silently ignore the stream given to it if application is in GUI mode (no console is attached) and redirect output to the debugger via OutputDebugString.

Such redirection makes sense only if passed stream is either stderr or stdout. Don't redirect any other stream to the debugger.

Reorder clauses in VPrintHelper to make condition more readable.

BUG=
R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/177413006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19688 ce2b1a6d-e550-0410-aec6-3dcde31c8c00