Use IsRuntimeEntry for RUNTIME_ENTRY comparison

Review URL: https://codereview.chromium.org/12702005
Patch from Haitao Feng <haitao.feng@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13929 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Remove unused field.

BUG=

Review URL: https://chromiumcodereview.appspot.com/12789004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13930 ce2b1a6d-e550-0410-aec6-3dcde31c8c00