Ignore multiple calls to ResourceLoaderBridge::Cancel
Merge remote-tracking branch 'origin/feature/blpwtk2/30.0.1599.101' into release/candidate
Remove usage of WebURL::spec()

There is a comment in WebURL indicating that this API will be removed.  Also,
the conversion to std::string does not work outside test code.
Merge remote-tracking branch 'origin/feature/bbEnhancements/30.0.1599.101' into release/candidate