DevTools: Always provide DOM.EventListener.location

Provide locations for EventListener's handleEvent() method or an object's constructor if it does not implement the EventListener interface.

R=pfeldman, yurys
BUG=340633

Review URL: https://codereview.chromium.org/145973019

git-svn-id: svn://svn.chromium.org/blink/trunk@166541 bbb929c8-8fbe-4397-9dbb-9b2b20218538