[7.2] Fix: Fullscreen sizing on old workpads (#37289) (#37292)

* fix: provide css value for workpads

old workpads were missing this value, this fixes scaling in fullscreen mode

* fix: make workpadCss a required prop

this will cause warnings in the future if the value is missing. also remove the unused css prop.

x-pack/plugins/canvas/public/components/workpad/workpad.js

@@ -25,13 +25,12 @@ export class Workpad extends React.PureComponent {
     isFullscreen: PropTypes.bool.isRequired,
     width: PropTypes.number.isRequired,
     height: PropTypes.number.isRequired,
-    workpadCss: PropTypes.string,
+    workpadCss: PropTypes.string.required,
     undoHistory: PropTypes.func.isRequired,
     redoHistory: PropTypes.func.isRequired,
     nextPage: PropTypes.func.isRequired,
     previousPage: PropTypes.func.isRequired,
     fetchAllRenderables: PropTypes.func.isRequired,
-    css: PropTypes.object,
     registerLayout: PropTypes.func.isRequired,
     unregisterLayout: PropTypes.func.isRequired,
   };

x-pack/plugins/canvas/public/state/selectors/workpad.js

@@ -6,7 +6,7 @@
 
 import { get, omit } from 'lodash';
 import { safeElementFromExpression, fromExpression } from '@kbn/interpreter/common';
-
+import { DEFAULT_WORKPAD_CSS } from '../../../common/lib/constants';
 import { append } from '../../lib/modify_path';
 import { getAssets } from './assets';
 
@@ -19,7 +19,11 @@ const appendAst = element => ({
 
 // workpad getters
 export function getWorkpad(state) {
-  return get(state, workpadRoot);
+  return {
+    // shim old workpads with new properties
+    css: DEFAULT_WORKPAD_CSS,
+    ...get(state, workpadRoot),
+  };
 }
 
 // should we split `workpad.js` to eg. `workpad.js` (full) and `persistentWorkpadStructure.js` (persistent.workpad)?