[fixed] shorthand signature for log
[fixed] shorthand signature for log

Summary: It wasn't accepting `label` as a positional value - now it is.

Reviewers: O2 Material Motion, O3 Material JavaScript platform reviewers, #material_motion

Tags: #material_motion

Differential Revision: http://codereview.cc/D3446

material-motion/material-motion-js,material-motion/material-motion-js,material-motion/material-motion-js