CheckHelper was only used within the macro itself. Furthermore, GCC
with -Winline was not always happy with the inline function. Simple
solution: Inline the inline function into the macro itself. Inlining
squared!

Review URL: https://chromiumcodereview.appspot.com/9295048

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10550 ce2b1a6d-e550-0410-aec6-3dcde31c8c00