Cleanup code

- Remove unused private function from DeclarativeTabModel
- Move debugs from WebViewTabCache behind debug flag
- Remove empty lines
Fix fetching of parentTabId (parent window)
Fix loading, loadProgress, and favicon properties to update when tab changes
Add basic tests for WebView

This commit adds basic test cases for new tab creation,
tab activation, closing of active tab, remove tab non active tab,
and url loading.
Merge pull request #54 from rainemak/newWebView

Add basic tests for WebView