Simplify specs.
[widget] Limit inspect spec to capybara-webkit.
[widget] Add more information to degraded inspect.
[widget] Make code using checkpoints more readable.
[widget] Clarify method name.
[widget] Remove unused method.
[widget] Add spec for .widget_delegator macro.
[widget] Make code using checkpoints more readable.
[widget] Remove duplicate method.
[widget] Remove #== and #!= delayed comparison specs.

This is a concern of Checkpoint, so no need to test it here.