Web Inspector: Charles Proxy errors opening har files exported from Safari (invalid...

Web Inspector: Charles Proxy errors opening har files exported from Safari (invalid startedDateTime)
https://bugs.webkit.org/show_bug.cgi?id=192959
<rdar://problem/46863411>

Patch by Joseph Pecoraro <pecoraro@apple.com> on 2018-12-20
Reviewed by Brian Burg.

* UserInterface/Views/NetworkTableContentView.js:
(WI.NetworkTableContentView.prototype.tableCellContextMenuClicked):
(WI.NetworkTableContentView.prototype._updateExportButton):
(WI.NetworkTableContentView.prototype._canExportHAR):
Disallow HAR export if we don't have load data, such as the requestSentDate for
the main resource or sub-resources.

(WI.NetworkTableContentView.prototype._HARResources):
Only export resources that have load data.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@239478 268f45cc-cd09-0410-ab3c-d52691b4dbfc