My goal was to move breakpoint API to native with minimal changes around, so on inspector side we use v8::debug::BreakpointId instead of String16, on v8::internal::Debug we use i::BreakPoint object instead of break point object created inside of debug.js.

There are a lot of opportunities how we can improve breakpoints (at least we can avoid some of linear lookups to speedup implementation) but I think that as first step we need to remove mirrors/debug.js APIs.

Drive by: debugger-script.js and usage of debugger context in inspector code base.

R=yangguo@chromium.org,jgruber@chromium.org,clemensh@chromium.org

Bug: v8:5510,chromium:652939
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I0b17972c39053dd4989bbe26db2bb0b88ca378f7
Reviewed-on: https://chromium-review.googlesource.com/593156Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47091}