fix(popover-edit): fix failing test

by making tested component always fit within the viewport
(viewport in tests is 1024 by 768)

Author: Goobles

src/material-experimental/popover-edit/popover-edit.spec.ts

@@ -177,7 +177,7 @@ class ElementDataSource extends DataSource<PeriodicElement> {
 
 @Component({
   template: `
-  <div #table style="margin: 16px">
+  <div #table style="margin: 16px; max-width: 700px">
     <mat-table editable [dataSource]="dataSource">
       <ng-container matColumnDef="before">
         <mat-cell *matCellDef="let element">