LegacyBrowser: fix Safari 13.1 (lacks logical nullish assignent) (#46260) (#46300)

(cherry picked from commit 0ee552dd65)

packages/grafana-data/src/transformations/transformers/labelsToFields.ts

@@ -70,7 +70,7 @@ export const labelsToFieldsTransformer: SynchronousDataTransformerInfo<LabelsToF
             continue;
           }
 
-          const uniqueValues = (uniqueLabels[labelName] ||= new Set());
+          const uniqueValues = uniqueLabels[labelName] ?? (uniqueLabels[labelName] = new Set()); // (Safari 13.1 lacks ??= support)
           uniqueValues.add(field.labels[labelName]);
         }
       }

public/app/features/dashboard/state/DashboardModel.ts

@@ -962,7 +962,7 @@ export class DashboardModel {
 
         for (const panel of row.panels) {
           // set the y gridPos if it wasn't already set
-          panel.gridPos.y ??= row.gridPos.y;
+          panel.gridPos.y ?? (panel.gridPos.y = row.gridPos.y); // (Safari 13.1 lacks ??= support)
           // make sure y is adjusted (in case row moved while collapsed)
           panel.gridPos.y -= yDiff;
           // insert after row