Inspector is moved to per-event-type callbacks instead of general v8::debug::SetDebugEventListener. It allows to:
- remove any usage of v8::Debug::EventDetails in debug-interface,
- avoid redundant JS call on each event to get properties of event objects,
- introduce better pure C++ API for these events later.

BUG=v8:5510
R=yangguo@chromium.org,jgruber@chromium.org,dgozman@chromium.org

Review-Url: https://codereview.chromium.org/2622253004
Cr-Commit-Position: refs/heads/master@{#42483}