Telemetry: smoothness measurement throws MissingTimelineMarker.
Telemetry: smoothness measurement throws MissingTimelineMarker.

Rather than throwing a generic LookupError exception when the timeline marker
cannot be found in the trace, throw a MissingTimelineMarker which is a subclass
of page_measurement.MeasurementFailure. These exceptios get caught by the page
runner.

Stop catching LookupError exeptions in _RunPage.

BUG=238864

Review URL: https://chromiumcodereview.appspot.com/23766009

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@222150 0039d316-1c4b-4281-b951-d872f2087c98

sahiljain/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,benschmaus/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,sahiljain/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult,benschmaus/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,sahiljain/catapult,sahiljain/catapult,catapult-project/catapult,SummerLW/Perf-Insight-Report,SummerLW/Perf-Insight-Report,sahiljain/catapult,catapult-project/catapult,benschmaus/catapult