perf: omit unnecessary work from ElectronRenderFrameObserver::ShouldNotifyClient()
- (perf) GetBlinkPreferences() returns a const&, so we can use that
reference instead of making a temporary copy
- (perf) Don't create url object unless it's needed.
- (refactor) Move is_main_world() and is_isolated_world() from the
header into an anonymous namespace in the .cc file so they can
be inlined and made constexpr
7cd23a4900