Also simplify ia32 and x64 handing of the trace_elements_transition flag.

R=jkummerow@chromium.org
BUG=none
TEST=array-literal-transitions.js

Review URL: http://codereview.chromium.org/8539011

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9979 ce2b1a6d-e550-0410-aec6-3dcde31c8c00