Revert 173136 "V8DOMActivityLogger should be owned by DOMWrapper..."

This broke interactive_ui_tests:
http://build.chromium.org/p/chromium.webkit/builders/Linux%20Tests/builds/36417/steps/interactive_ui_tests/logs/stdio

> V8DOMActivityLogger should be owned by DOMWrapperWorld
> 
> - Currently V8DOMActivityLogger is owned by a static hash map and cached on V8PerContextData. This is mis-designed. Given that an ActivityLogger should conceptually be associated with a world, V8DOMActivityLogger should be owned by DOMWrapperWorld. This CL makes the change.
> 
> - The reason why we were caching V8DOMActivityLogger on V8PerContextData is that DOMWrapperWorld::current() was slower than V8PerContextData::from(). Recently I optimized DOMWrapperWorld::current() and now it's as fast as V8PerContextData::from(). So I think it's now OK to make this change.
> 
> Review URL: https://codereview.chromium.org/264853002

TBR=haraken@chromium.org

Review URL: https://codereview.chromium.org/269713002

git-svn-id: svn://svn.chromium.org/blink/trunk@173159 bbb929c8-8fbe-4397-9dbb-9b2b20218538