[DevTools] removed Breakpoint._currentState
[DevTools] removed Breakpoint._currentState

Current state on breakpoint shared between different models is hack
that should never work.

R=73889f071ff743ad62763f13ff61c52ca3ee19d0@chromium.org

Bug: none
Change-Id: I60a0e5774c47c38a0f5f251f9e9d5f2437ceb9b4
Reviewed-on: https://chromium-review.googlesource.com/1179262
Reviewed-by: Andrey Lushnikov <73889f071ff743ad62763f13ff61c52ca3ee19d0@chromium.org>
Commit-Queue: Andrey Lushnikov <73889f071ff743ad62763f13ff61c52ca3ee19d0@chromium.org>
Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#583934}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 9c39f918d0601422526a5b2f9d7798dfa553b67d
ChromeDevTools/devtools-frontend,dart-archive/devtools-frontend,dart-archive/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,dart-archive/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,dart-archive/devtools-frontend,dart-archive/devtools-frontend,ChromeDevTools/devtools-frontend,dart-archive/devtools-frontend