Fix a memory leak in scalar-span.
Fix a memory leak in scalar-span.

removeEventListener (for both native event targets and tr.b.EventTarget) only
works if the handler is the exact same function object as was passed to
addEventListener.
Binding a function creates a new function object.
If the removeEventListener() call site also calls bind(), then
removeEventListener() will silently fail to actually remove the listener, and
memory will leak.

Review-Url: https://codereview.chromium.org/2957553002

benschmaus/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,benschmaus/catapult,benschmaus/catapult,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,catapult-project/catapult-csm