This test does the following:
-Makes a call to replaceState()
-Makes sure the history length is correct
-Makes a call to pushState()
-Makes sure the history length is correct
-Goes back, and makes sure the popstate event is correct
-Goes forward, and makes sure the popstate event is correct

History length is 1
History length is 2
State popped - OriginalHistoryItem (type string)
State popped - NewHistoryItem (type string)