Fixed error message for exceeding maximum struct nesting. It got broken in r2423. We were referring to field-name as struct-name. This patch fixes the regression and also improves the error message by adding the field-name. BUG=angle:459 R=kbr@chromium.org Review URL: https://codereview.appspot.com/12891043 Change-Id: I9ac9a8dafcad1857f7d39e6d494e457d1fc50f70 Reviewed-on: https://chromium-review.googlesource.com/190530 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Reviewed-by: Nicolas Capens <nicolascapens@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>