Introduce Protocol.Domain.method(args) and Protocol.Domain.onEventName() instead.
Renamed InspectorTest.evaluateInPage -> InspectorTest.addScript.
Improved InspectorTest.logMessage.

BUG=chromium:635948
R=dgozman@chromium.org,alph@chromium.org

Review-Url: https://codereview.chromium.org/2390733002
Cr-Commit-Position: refs/heads/master@{#39942}