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)

}
    }
    ctx.putImageData(chunkImgData, 0, i * FULL_CHUNK_HEIGHT);
  }
}
function copyCtxState(sourceCtx, destCtx) {
  const properties = [
    "strokeStyle",
    "fillStyle",
    "fillRule",
    "globalAlpha",
    "lineWidth",
    "lineCap",
    "lineJoin",
    "miterLimit",
    "globalCompositeOperation",
    "font",
  ];
  for (let i = 0, ii = properties.length; i < ii; i++) {
    const property = properties[i];
    if (sourceCtx[property] !== undefined) {
      destCtx[property] = sourceCtx[property];
    }
  }
  if (sourceCtx.setLineDash !== undefined) {
    destCtx.setLineDash(sourceCtx.getLineDash());
    destCtx.lineDashOffset = sourceCtx.lineDashOffset;
  }
}
function resetCtxToDefault(ctx) {