Provide list of step-in source positions in JS Debug API

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/15960016

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15322 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Allow debugger evaluate expressions to mute local variables

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/17636007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15323 ce2b1a6d-e550-0410-aec6-3dcde31c8c00