fix(dirty_checking): don't include marker records in DirtyCheckingChangeDetector.count

There was a mistake in which marker records were being counted, due to mistakenly referencing the
value DirtyCheckingChangeDetector._MODE_MARKER_, when the number is actually in file scope and not
bound to the DirtyCheckingChangeDetector class.
fix(testing): add raw value to Logger, rather than value.toString()

Don't string-ify values added to logger, so that it may compare object identities in specs.
fix(linked_list): correctly import and initialize _ArgHandler* lists and items

Previously, these classes were not being imported correctly (resulting in attempting to call a
property of an undefined value). Additionally, the next and previous properties of _ArgHandler
items were never initialized. These problems are addressed in this fix.