DevTools: fix test inspector/elements/inline-style-title.html flakiness

This patch fixes flakiness of the
inspector/elements/inline-style-title.html test.

BUG=
TBR=pfeldman

Review URL: https://codereview.chromium.org/177413002

git-svn-id: svn://svn.chromium.org/blink/trunk@167681 bbb929c8-8fbe-4397-9dbb-9b2b20218538