[telemetry] Separate dynamic attributes from page members.
[telemetry] Separate dynamic attributes from page members.

Fix for http://crrev.com/192096. Sigh

TBR=marja@chromium.org
BUG=None.
TEST=None.

Review URL: https://codereview.chromium.org/13587006

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@192174 0039d316-1c4b-4281-b951-d872f2087c98

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