I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

if (isNum(glyph)) {
          spacingLength = (spacingDir * glyph * fontSize) / 1000;
          this.ctx.translate(spacingLength, 0);
          current.x += spacingLength * textHScale;
          continue;
        }
        const spacing = (glyph.isSpace ? wordSpacing : 0) + charSpacing;
        const operatorList = font.charProcOperatorList[glyph.operatorListId];
        if (!operatorList) {
          warn(`Type3 character "${glyph.operatorListId}" is not available.`);
          continue;
        }
        if (this.contentVisible) {
          this.processingType3 = glyph;
          this.save();
          ctx.scale(fontSize, fontSize);
          ctx.transform.apply(ctx, fontMatrix);
          this.executeOperatorList(operatorList);
          this.restore();
        }
        const transformed = Util.applyTransform([glyph.width, 0], fontMatrix);
        width = transformed[0] * fontSize + spacing;
        ctx.translate(width, 0);
        current.x += width * textHScale;
      }
      ctx.restore();
      this.processingType3 = null;
    }
    
    setCharWidth(xWidth, yWidth) {