Remove heap snapshot worker files from 'profiler' module

These files are used only in the worker and should not be compiled as part of the front-end page. The files were extracted into heap_snapshot_shared_worker module (which doesn't compile yet, will fix that in a follow-up change).

compile_frontend.py is extended to accept 'standalone' modules. At the moment there is only front_end_page_modules which enumerates all modules that can be loaded in the front-end page. I'm going to add heap_snapshot_worker_modules and standalone modules for other workers.

BUG=None
R=alph@chromium.org, apavlov@chromium.org

Review URL: https://codereview.chromium.org/143213002

git-svn-id: svn://svn.chromium.org/blink/trunk@165402 bbb929c8-8fbe-4397-9dbb-9b2b20218538