message: [WebGL Renderer] Fix the styles in the test harness
diff: -import { CharCellGrid } from "extraterm-char-cell-grid";
  +import { CharCellGrid, STYLE_MASK_BOLD, STYLE_MASK_ITALIC, STYLE_MASK_STRIKETHROUGH, UNDERLINE_STYLE_NORMAL } from "extraterm-char-cell-grid";
  import * as easta from "easta";
  @@ -161,11 +161,6 @@ export class VtOutputDevice implements OutputDevice {
  }
  }
  -const STYLE_MASK_BOLD = 1;
  -const STYLE_MASK_UNDERLINE = 2;
  -const STYLE_MASK_ITALIC = 4;
  -const STYLE_MASK_STRIKETHROUGH = 8;
  -
  export class CellGridOutputDevice implements OutputDevice {
  private x = 0;
  private y = 0;
  @@ -239,7 +234,7 @@ export class CellGridOutputDevice implements OutputDevice {
  style |= STYLE_MASK_ITALIC;
  }
  if (this.isUnderline) {
  - style |= STYLE_MASK_UNDERLINE;
  + style |= UNDERLINE_STYLE_NORMAL;
  }
  if (this.isStrikethrough) {
  style |= STYLE_MASK_STRIKETHROUGH;
  