function timingFunctionMatch(str, lax) {
        return bezierCurveMatch(str, lax) || stepsMatch(str, lax);
    }
Match a timing function value from a CSS Declaration or Value.

Matches returned from this function must be handled in
BezierCurveEditor._getCubicBezierCoords().

@param {string} str  Input string.
@param {!boolean} lax  Parsing mode where:
         lax=false Input is a Full or partial line containing CSS Declaration.
                   This is the more strict search used for initial detection.
         lax=true  Input is a previously parsed value. This is the less strict search
                   used to convert previously parsed values to RegExp match format.
@return {!RegExpMatch}