Attach (recommended) or Link to PDF file here:
issue13500 (in test corpus)

This regressed when landing #13566. 

What is the expected behavior? (add screenshot)
<img width="664" alt="image" src="https://user-images.githubusercontent.com/942640/122467522-7bc8aa80-cf6f-11eb-9d4d-311eb7c64fb2.png">


What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/942640/122467565-85eaa900-cf6f-11eb-9c10-8a8686ed440c.png)


? getMeasurement(attributes.spaceAbove, "0pt")
      : "";
    this.spaceBelow = attributes.spaceBelow
      ? getMeasurement(attributes.spaceBelow, "0pt")
      : "";
    this.tabDefault = attributes.tabDefault
      ? getMeasurement(this.tabDefault)
      : "";
    this.tabStops = (attributes.tabStops || "")
      .trim()
      .split(/\s+/)
      .map((x, i) => (i % 2 === 1 ? getMeasurement(x) : x));
    this.textIndent = attributes.textIndent
      ? getMeasurement(attributes.textIndent, "0pt")
      : "";
    this.use = attributes.use || "";
    this.usehref = attributes.usehref || "";
    this.vAlign = getStringOption(attributes.vAlign, [
      "top",
      "bottom",
      "middle",
    ]);
    this.widows = getInteger({
      data: attributes.widows,
      defaultValue: 0,
      validate: x => x >= 0,
    });
    this.hyphenation = null;
  }
  [$toStyle]() {