chore(overlays): fix demo by adding boundariesElement to popup config

packages/overlays/stories/local-overlay-placement.stories.js

@@ -83,6 +83,7 @@ storiesOf('Local Overlay System|Local Overlay Placement', module)
             },
             preventOverflow: {
               enabled: false /* disables shifting/sliding behavior on secondary axis */,
+              boundariesElement: 'viewport',
               padding: 32 /* when enabled, this is the viewport-margin for shifting/sliding */,
             },
             flip: {

packages/popup/stories/index.stories.js

@@ -109,6 +109,7 @@ storiesOf('Local Overlay System|Popup', module)
               },
               preventOverflow: {
                 enabled: true /* disables shifting/sliding behavior on secondary axis */,
+                boundariesElement: 'viewport',
                 padding: 16 /* when enabled, this is the viewport-margin for shifting/sliding */,
               },
               flip: {

packages/tooltip/stories/index.stories.js

@@ -109,6 +109,7 @@ storiesOf('Local Overlay System|Tooltip', module)
               },
               preventOverflow: {
                 enabled: false /* disables shifting/sliding behavior on secondary axis */,
+                boundariesElement: 'viewport',
                 padding: 16 /* when enabled, this is the viewport-margin for shifting/sliding */,
               },
               flip: {