code: function coerceNumberProperty(value, fallbackValue) {
      if (fallbackValue === void 0) { fallbackValue = 0; }
      // parseFloat(value) handles most of the cases we're interested in (it treats null, empty string,
      // and other non-number values as NaN, where Number just uses 0) but it considers the string
      // '123hello' to be a valid number. Therefore we also check if Number(value) is NaN.
      return isNaN(parseFloat(/** @type {?} */ (value))) || isNaN(Number(value)) ? fallbackValue : Number(value);
  }
docs: Coerces a data-bound value (typically a string) to a number.
  @param {?} value
  @param {?=} fallbackValue
  @return {?}