Fix elastic window resize handling (#2840)

Fix elastic window resize handling

__tests__/src/components/WorkspaceElasticWindow.test.js

@@ -88,8 +88,8 @@ describe('WorkspaceElasticWindow', () => {
         .props()
         .onResize('myevent', 'direction', {
           style: {
-            height: 200,
-            width: 400,
+            height: '200px',
+            width: '400px',
           },
         }, {}, { x: 0, y: 0 });
       expect(mockOnResize).toHaveBeenCalledWith('1', {

src/components/WorkspaceElasticWindow.js

@@ -42,8 +42,8 @@ class WorkspaceElasticWindow extends React.Component {
         }}
         onResize={(e, direction, ref, delta, position) => {
           updateElasticWindowLayout(layout.windowId, {
-            height: ref.style.height - companionWindowDimensions.height,
-            width: ref.style.width - companionWindowDimensions.width,
+            height: Number.parseInt(ref.style.height, 10) - companionWindowDimensions.height,
+            width: Number.parseInt(ref.style.width, 10) - companionWindowDimensions.width,
             x: position.x - offsetX,
             y: position.y - offsetY,
           });