Adjusted highlighting tooltip size
Adjusted highlighting tooltip size

Summary: Now the image no longer extends well beyond the visible tooltip. This stops uses accidentally clicking on the tooltip when they mean to click elsewhere.

Test Plan:
  # Go to http://localhost:8080/mission/sat/tasks/6383833230344192
  # Play with the highlighting tool to see what registers as clicking on the tooltip and what doesn't

Reviewers: sean, mattdunnrankin

Reviewed By: mattdunnrankin

Subscribers: jared

Differential Revision: https://phabricator.khanacademy.org/D29750

ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus,ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus