Fixed callback to tts.speak.
Fixed callback to tts.speak.

Previously, the callback to tts.speak would never be called. It is now
called correctly, and arguments are correctly juggled so that this will
occur even if the optional options parameter isn't specified.

R=raymes@chromium.org

Review URL: https://codereview.chromium.org/1588833002 .

chromium/caterpillar,chromium/caterpillar,chromium/caterpillar