||See testing/talos/talos/tests/devtools/addon/content/pages/custom/debugger/app/src for the details
about the pages used for these tests.
||These methods are used for working with debugger state changes in order
to make it easier to manipulate the ui and test different behavior. These
methods roughly reflect those found in debugger/test/mochi/head.js with
a few exceptions. The `dbg` object is not exactly the same, and the methods
have been simplified. We may want to consider unifying them in the future