Switch CTI runtime calls to the fastcall calling convention

Switch CTI runtime calls to the fastcall calling convention

Reviewed by Cameron Zwarich

Basically this means that we get to store the argument for CTI
calls in the ECX register, which saves a register->memory write
and subsequent memory->register read.

This is a 1.7% progression in SunSpider and 2.4% on commandline
v8 tests on Windows

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@37406 268f45cc-cd09-0410-ab3c-d52691b4dbfc