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)

accent.fontChar,
              scaledAccentX,
              scaledAccentY,
              patternTransform,
              resetLineWidthToOne
            );
          }
        }
      }
      let charWidth;
      if (vertical) {
        charWidth = width * widthAdvanceScale - spacing * fontDirection;
      } else {
        charWidth = width * widthAdvanceScale + spacing * fontDirection;
      }
      x += charWidth;
      if (restoreNeeded) {
        ctx.restore();
      }
    }
    if (vertical) {
      current.y -= x;
    } else {
      current.x += x * textHScale;
    }
    ctx.restore();
    this.compose();
    return undefined;
  }
  showType3Text(glyphs) {