node.cc: node exception handler is verbose

All TryCatch blocks used in node are now verbose, so that V8 debugger
can break on uncaught exceptions.

See comment in `deps/v8/include/v8.h` for explanation:
>  By default, exceptions that are caught by an external exception
>  handler are not reported.  Call SetVerbose with true on an
>  external exception handler to have exceptions caught by the
>  handler reported as if they were not caught.

The flag is used by `Isolate::ShouldReportException()`, which is called
by `Isolate::DoThrow()` to decide whether an exception is considered
uncaught.