Replace ScriptState in core/inspector/ with NewScriptState

- This is one of incremental steps to replace ScriptState with NewScriptState. This CL does the replacement for core/inspector/.

- This CL temporarily introduces NewScriptState::oldScriptState (which returns a ScriptState) and ScriptState::newScriptState (which returns a NewScriptState) to achieve the replacement incrementally. I'll remove these methods once I complete the replacement (which will happen in one week).

- This CL removes ScriptStateProtectedPtr, and instead directly cache ScopedPersistent in ConsoleMessage and ScriptArgument.

- No change in behavior.

BUG=357144

Review URL: https://codereview.chromium.org/246643003

git-svn-id: svn://svn.chromium.org/blink/trunk@172378 bbb929c8-8fbe-4397-9dbb-9b2b20218538