Minor Native Client specific changes to files in src.

These changes are required for Native Client validation and to
accomodate the limitations of the NaCl runtime.

BUG=2614

Review URL: https://chromiumcodereview.appspot.com/13704002
Patch from Brad Chen <bradchen@google.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14187 ce2b1a6d-e550-0410-aec6-3dcde31c8c00