BatteryManager.getBattery(): gracefully bail on context-detached use.

Semi-blind fix for fuzzer-generated crash on accessing a BatteryManager
lacking an execution context.

Added a non-reproducing test to verify detached use, along with reducing
test duplication for similar tests.

R=jochen
BUG=457010

Review URL: https://codereview.chromium.org/915033002

git-svn-id: svn://svn.chromium.org/blink/trunk@190031 bbb929c8-8fbe-4397-9dbb-9b2b20218538
16 files changed
tree: 367e73854dad0b0eff353f9964225b18968e0496
  1. third_party/