If a String object contains unicode, the returned {ToCString()} may
actually longer than the {length()} of the String.
But it's always null-terminated, so we can just print it without
explicitly passing a length.

R=ahaas@chromium.org

Change-Id: I3398f151d70ed459ecd8093ea18409670a7374c7
Reviewed-on: https://chromium-review.googlesource.com/548058
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46225}