Tests that console is cleared upon clear() eval in console.
=== Before clear ===
-one console-command-clear.html:9
-two console-command-clear.html:10
-three console-command-clear.html:11
+console-command-clear.html:9 one
+console-command-clear.html:10 two
+console-command-clear.html:11 three
=== After clear ===
undefined