Improve test cases for network information APIs

Improve test cases for network information APIs
https://bugs.webkit.org/show_bug.cgi?id=90162

Reviewed by Adam Barth.

Existing implementation doesn't test port implementation in network info APIs.
This patch lets test cases use bandwidth and metered functions implemented by port layer.

In addition, expected results need to check return type instead of property name.

Source/WebCore:

No new tests. Covered by existing tests.

* Modules/networkinfo/NetworkInfoConnection.cpp:
(WebCore::NetworkInfoConnection::bandwidth):
(WebCore::NetworkInfoConnection::metered):

LayoutTests:

* networkinformation/add-listener-from-callback-expected.txt:
* networkinformation/basic-all-types-of-events-expected.txt:
* networkinformation/basic-operation-expected.txt:
* networkinformation/multiple-frames-expected.txt:
* networkinformation/script-tests/add-listener-from-callback.js:
(checkNetworkInformation):
* networkinformation/script-tests/basic-all-types-of-events.js:
(checkNetworkInformation):
* networkinformation/script-tests/basic-operation.js:
* networkinformation/script-tests/multiple-frames.js:
(checkNetworkInformation):
(checkChildNetworkInformation):
* networkinformation/script-tests/updates.js:
(checkNetworkInformation):
* networkinformation/updates-expected.txt:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121754 268f45cc-cd09-0410-ab3c-d52691b4dbfc