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)

tmpCtx.rect(0, 0, tmpCtx.canvas.width, tmpCtx.canvas.height);
        tmpCtx.setTransform.apply(tmpCtx, owner.baseTransform);
        if (this.matrix) {
          tmpCtx.transform.apply(tmpCtx, this.matrix);
        }
        applyBoundingBox(tmpCtx, this._bbox);
        tmpCtx.fillStyle = this._createGradient(tmpCtx);
        tmpCtx.fill();
        pattern = ctx.createPattern(tmpCanvas.canvas, "repeat");
        this.cachedCanvasPatterns.set(this, pattern);
      }
    } else {
      
      applyBoundingBox(ctx, this._bbox);
      pattern = this._createGradient(ctx);
    }
    if (!shadingFill) {
      const domMatrix = new DOMMatrix(inverse);
      try {
        pattern.setTransform(domMatrix);
      } catch (ex) {
        
        
        warn(`RadialAxialShadingPattern.getPattern: "${ex?.message}".`);
      }
    }
    return pattern;
  }
}
function drawTriangle(data, context, p1, p2, p3, c1, c2, c3) {