src: break on uncaught exception

Most TryCatch blocks have SetVerbose flag on, this tells V8 to report
uncaught exceptions to debugger.

FatalException handler is called from V8 Message listener instead from
the place where TryCatch was used. Otherwise uncaught exceptions are
logged twice.

See comment in `deps/v8/include/v8.h` for explanation of SetVerbose
flag:

>  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.