function OTLayoutEngine(font) {
    this.font = font;
    this.glyphInfos = null;
    this.plan = null;
    this.GSUBProcessor = null;
    this.GPOSProcessor = null;
    this.fallbackPosition = true;

    if (font.GSUB) {
      this.GSUBProcessor = new GSUBProcessor(font, font.GSUB);
    }

    if (font.GPOS) {
      this.GPOSProcessor = new GPOSProcessor(font, font.GPOS);
    }
  }
Gets the exact bounding box of the path by evaluating curve segments.
Slower to compute than the control box, but more accurate.
@type {BBox}