Simplify document outline

Convert some `section` elements to `div`s for a less chattery document
structure.

src/sidebar/components/annotation-body.js

@@ -39,7 +39,7 @@ export default function AnnotationBody({
   const showTagList = !isEditing && tags.length > 0;
 
   return (
-    <section className="annotation-body">
+    <div className="annotation-body">
       {showExcerpt && (
         <Excerpt
           collapse={isCollapsed}
@@ -78,7 +78,7 @@ export default function AnnotationBody({
       )}
       {showTagList && <TagList annotation={annotation} tags={tags} />}
       {isEditing && <TagEditor onEditTags={onEditTags} tagList={tags} />}
-    </section>
+    </div>
   );
 }
 

src/sidebar/components/annotation-quote.js

@@ -23,7 +23,7 @@ function AnnotationQuote({ annotation, isFocused, settings = {} }) {
   const documentLanguage = '';
 
   return (
-    <section
+    <div
       className={classnames('annotation-quote', {
         'is-orphan': isOrphan(annotation),
         'is-focused': isFocused,
@@ -43,7 +43,7 @@ function AnnotationQuote({ annotation, isFocused, settings = {} }) {
           {quote(annotation)}
         </blockquote>
       </Excerpt>
-    </section>
+    </div>
   );
 }
 

src/sidebar/components/test/thread-list-test.js

@@ -214,13 +214,13 @@ describe('ThreadList', () => {
    * Get the blank spacer `<div>` that reserves space for non-rendered threads
    * above the viewport.
    */
-  const getUpperSpacer = wrapper => wrapper.find('div').first();
+  const getUpperSpacer = wrapper => wrapper.find('div > div').first();
 
   /**
    * Get the blank spacer `<div>` that reserves space for non-rendered threads
    * below the viewport.
    */
-  const getLowerSpacer = wrapper => wrapper.find('div').last();
+  const getLowerSpacer = wrapper => wrapper.find('div > div').last();
 
   it('renders dimensional elements above and below visible threads', () => {
     const wrapper = createComponent();

src/sidebar/components/thread-list.js

@@ -174,7 +174,7 @@ function ThreadList({ thread, $rootScope }) {
   }, [visibleThreads]);
 
   return (
-    <section>
+    <div>
       <div style={{ height: offscreenUpperHeight }} />
       {visibleThreads.map(child => (
         <div className="thread-list__card" id={child.id} key={child.id}>
@@ -182,7 +182,7 @@ function ThreadList({ thread, $rootScope }) {
         </div>
       ))}
       <div style={{ height: offscreenLowerHeight }} />
-    </section>
+    </div>
   );
 }