[webapi] Add 2 TCs for missing test point and delete unused files in tct...

Impacted Suites: tct-webstorage-w3c-tests
Impacted TCs num: New 2, Update 0, Delete 16
Unit test platform: IVI
IVI test result summary: Pass 2, Fail 0, Blocked 0

Remove TC check point repeat:
event_constructor_js.html >>
  StorageEvent_constructor_key_null.html, StorageEvent_constructor_newValue_null.html,               StorageEvent_constructor_oldValue_null, StorageEvent_constructor_url_null, StorageEvent_storageArea_initial_value
storage_local_builtins.html >>
  window_localStorage_exist.html
storage_local_clear_js.html >>
  storage_local_clear.html
storage_local_getitem_js.html >>
  storage_local_getitem.html
storage_local_length_js.html >>
  storage_local_length.html
storage_local_removeitem_js.html >>
  storage_local_removeitem.html
storage_local_security.html >>
  storage_local_getitem.html
storage_local_setitem_js.html >>
  storage_local_setitem.html
storage_session_builtins.html >>
  window_sessionStorage_exist.html
storage_session_clear_js.html >>
  storage_session_clear.html
storage_session_getitem_js.html >>
  storage_session_getitem.html
storage_session_length_js.html >>
  storage_session_length.html
storage_session_removeitem_js.html >>
  storage_session_removeitem.html
storage_session_setitem_js.html >>
  storage_session_setitem.html
window_localStorage_clear_base.html >>
  storage_local_clear.html
window_sessionStorage_clear_base.html >>
  storage_session_clear.html