DevTools: Fix newly uncovered compilation errors

These errors were detected using the new compilation approach
suggested in https://codereview.chromium.org/573453004/.

R=loislo
NOTRY=true

Review URL: https://codereview.chromium.org/585633005

git-svn-id: svn://svn.chromium.org/blink/trunk@182318 bbb929c8-8fbe-4397-9dbb-9b2b20218538