(core) Improve printing of tables, fix printing of charts, add a browser test.

Summary:
- Include column headers on each page for printing tables.
- Avoid page-breaks inside rows or cards of a card-list.
- Fix printing of charts that did not show up at all before.
- Add a browser test, not great, but somewhat functional.

Test Plan: New test, plus tested manually. Column headers work on Chrome and Firefox (not Safari).

Reviewers: paulfitz

Reviewed By: paulfitz

Differential Revision: https://phab.getgrist.com/D2636

app/client/components/ChartView.ts

@@ -7,6 +7,7 @@ import {fromKoSave} from 'app/client/lib/fromKoSave';
 import {loadPlotly, PlotlyType} from 'app/client/lib/imports';
 import * as DataTableModel from 'app/client/models/DataTableModel';
 import {ViewFieldRec, ViewSectionRec} from 'app/client/models/DocModel';
+import {reportError} from 'app/client/models/errors';
 import {KoSaveableObservable, ObjObservable} from 'app/client/models/modelUtil';
 import {SortedRowSet} from 'app/client/models/rowset';
 import {cssRow} from 'app/client/ui/RightPanel';
@@ -131,6 +132,10 @@ export class ChartView extends Disposable {
     this.autoDispose(this.sortedRows.getKoArray().subscribe(this._update));
   }
 
+  public prepareToPrint(onOff: boolean) {
+    Plotly.relayout(this._chartDom, {}).catch(reportError);
+  }
+
   protected onTableLoaded() {
     (BaseView.prototype as any).onTableLoaded.call(this);
     this._update();