message: Add some debug methods to `CharCellGrid`
diff: @@ -230,6 +230,22 @@ export class CharCellGrid {
  this.setCell(x, y, SpaceCell);
  }
  + formatCellDebug(x: number, y: number): string {
  + return (`{ char: '${String.fromCodePoint(this.getCodePoint(x, y))}', ` +
  + `codePoint: ${this.getCodePoint(x, y)}, ` +
  + `extraWidth: ${this.getCharExtraWidth(x, y)}, ` +
  + `ligature: ${this.getLigature(x, y)}, ` +
  + `}`);
  + }
  +
  + formatRowDebug(y: number): string {
  + const result = [];
  + for (let i=0; i<this.width; i++) {
  + result.push("" + i + ": " + this.formatCellDebug(i, y));
  + }
  + return result.join("\n");
  + }
  +
  setCodePoint(x: number, y: number, codePoint: number): void {
  const offset = (y * this.width + x) * CELL_SIZE_BYTES;
  