message: Clean up resources and refs in `TerminalCanvas.dispose()`
diff: @@ -305,10 +305,27 @@ export class TerminalCanvas extends ThemeableElementBase implements AcceptsConfi
  kid.element.dispose();
  }
  }
  + this._childElementList = [];
  +
  + while(this._scrollArea.hasChildNodes()) {
  + this._scrollArea.removeChild(this._scrollArea.children[0]);
  + }
  +
  + this._virtualScrollArea = null;
  + this._stashArea = null;
  if (this._scrollContainer != null) {
  TerminalCanvas._resizeNotifier.unobserve(this._scrollContainer);
  }
  + this._scrollContainer = null;
  +
  + this._scrollBar = null;
  + this._cssStyleElement = null;
  + this._terminalViewer = null;
  + this._lastChildWithFocus = null;
  + this._scrollArea = null;
  +
  + this._onBeforeSelectionChangeEmitter.dispose();
  }
  setConfigDatabase(configManager: ConfigDatabase): void {
  