php: fixed Math.exp for NaN

git-svn-id: http://haxe.googlecode.com/svn/trunk@6175 f16182fa-f095-11de-8f43-4547254af6c6
php: fixed Math.exp for NaN

git-svn-id: http://haxe.googlecode.com/svn/trunk@6176 f16182fa-f095-11de-8f43-4547254af6c6
php: added test for issue #1048

git-svn-id: http://haxe.googlecode.com/svn/trunk@6177 f16182fa-f095-11de-8f43-4547254af6c6
php: fixed issue #1048

git-svn-id: http://haxe.googlecode.com/svn/trunk@6178 f16182fa-f095-11de-8f43-4547254af6c6