Link to PDF file (or attach file here):
https://issues.apache.org/jira/secure/attachment/12650283/000004_ShadingPatternTextPDF.pdf

Configuration:
- Web browser and its version: FF 51.0.1 32bit
- Operating system and its version: W7
- PDF.js version: latest

Steps to reproduce the problem:
display file

What is the expected behavior? (add screenshot)
![ok](https://cloud.githubusercontent.com/assets/6665575/23339534/5ff2de9c-fc25-11e6-837e-0fdaf81b4ca9.png)

What went wrong? (add screenshot)
![nok](https://cloud.githubusercontent.com/assets/6665575/23339536/63f7a37e-fc25-11e6-813c-cc218cc4def3.png)

possibly similar problem:
https://www.pdflib.com/fileadmin/pdflib/Cookbook/pdf/color_gradient.pdf (shaded text completely missing)
https://issues.apache.org/jira/secure/attachment/12630566/pslib-shading.pdf (page 4, part of text missing)
https://issues.apache.org/jira/secure/attachment/12652009/pattern-shading-2-4-idMatrix.pdf (some text missing)
https://issues.apache.org/jira/secure/attachment/12652010/pattern-shading-2-4-noMatrix.pdf (some text missing)

this.ctx.closePath();
  }
  stroke(consumePath) {
    consumePath = typeof consumePath !== "undefined" ? consumePath : true;
    const ctx = this.ctx;
    const strokeColor = this.current.strokeColor;
    
    
    ctx.globalAlpha = this.current.strokeAlpha;
    if (this.contentVisible) {
      if (typeof strokeColor === "object" && strokeColor?.getPattern) {
        const lineWidth = this.getSinglePixelWidth();
        ctx.save();
        ctx.strokeStyle = strokeColor.getPattern(
          ctx,
          this,
          ctx.mozCurrentTransformInverse
        );
        
        ctx.lineWidth = Math.max(lineWidth, this.current.lineWidth);
        ctx.stroke();
        ctx.restore();
      } else {
        const lineWidth = this.getSinglePixelWidth();
        if (lineWidth < 0 && -lineWidth >= this.current.lineWidth) {
          
          
          ctx.save();
          ctx.resetTransform();
          ctx.lineWidth = Math.round(this._combinedScaleFactor);