Make diff specs compatible w/ BootstrapVue 2

spec/frontend/diffs/components/diff_file_header_spec.js

@@ -92,6 +92,7 @@ describe('DiffFileHeader component', () => {
       localVue,
       store,
       sync: false,
+      attachToDocument: true,
     });
   };
 

spec/frontend/diffs/components/diff_gutter_avatars_spec.js

@@ -15,10 +15,11 @@ describe('DiffGutterAvatars', () => {
   const createComponent = (props = {}) => {
     wrapper = shallowMount(DiffGutterAvatars, {
       localVue,
-      sync: false,
       propsData: {
         ...props,
       },
+      sync: false,
+      attachToDocument: true,
     });
   };
 

spec/frontend/diffs/components/edit_button_spec.js

@@ -10,8 +10,9 @@ describe('EditButton', () => {
   const createComponent = (props = {}) => {
     wrapper = shallowMount(EditButton, {
       localVue,
-      sync: false,
       propsData: { ...props },
+      sync: false,
+      attachToDocument: true,
     });
   };