The section name is printed two times currently: Once in
{WasmSectionIterator::next()}, once in
{ModuleDecoderImpl::DecodeSection}.
This is confusing when looking at the trace output, hence remove one of
the outputs.

R=ahaas@chromium.org

Change-Id: Icc699d5eb0e39325d2849ea6c345b9522985003b
Reviewed-on: https://chromium-review.googlesource.com/756703Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49175}