Fix a memory leak in mouse handling.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/2449009
diff --git a/src/IBusChewingEngine.gob b/src/IBusChewingEngine.gob
index ee7eb95..a98bb9c 100644
--- a/src/IBusChewingEngine.gob
+++ b/src/IBusChewingEngine.gob
@@ -757,6 +757,7 @@
 	    }
 	    ibus_chewing_engine_set_status_flag(self, ENGINE_STATUS_NEED_COMMIT);
 	    chewing_handle_Default(self->context, keys[index]);
+	    chewing_free(keys);
 	    self_update(self);
 	} else {
 	    G_DEBUG_MSG(3,"[I3] handle_cadidate_clicked() ... Wrong mode: %u", self->inputMode);