fix async highlight not async

src/marked.js

@@ -76,20 +76,22 @@ function marked(src, opt, callback) {
     marked.walkTokens(tokens, function(token) {
       if (token.type === 'code') {
         pending++;
-        highlight(token.text, token.lang, function(err, code) {
-          if (err) {
-            return done(err);
-          }
-          if (code != null && code !== token.text) {
-            token.text = code;
-            token.escaped = true;
-          }
-
-          pending--;
-          if (pending === 0) {
-            done();
-          }
-        });
+        setTimeout(() => {
+          highlight(token.text, token.lang, function(err, code) {
+            if (err) {
+              return done(err);
+            }
+            if (code != null && code !== token.text) {
+              token.text = code;
+              token.escaped = true;
+            }
+
+            pending--;
+            if (pending === 0) {
+              done();
+            }
+          });
+        }, 0);
       }
     });
 

test/unit/marked-spec.js

@@ -310,7 +310,7 @@ text 1
   });
 
   it('should call callback for each error in highlight', (done) => {
-    highlight.and.callFake((lang, text, callback) => {
+    highlight.and.callFake((text, lang, callback) => {
       callback(new Error('highlight error'));
     });
 
@@ -328,6 +328,29 @@ text 1
       }
     });
   });
+
+  it('should highlight codeblocks when not async', (done) => {
+    highlight.and.callFake((text, lang, callback) => {
+      callback(null, `async ${text || ''}`);
+    });
+
+    marked(markdown, { highlight }, (err, html) => {
+      if (err) {
+        fail(err);
+      }
+
+      expect(html).toBe(`<pre><code class="language-lang1">async text 1</code></pre>
+<blockquote>
+<pre><code class="language-lang2">async text 2</code></pre>
+</blockquote>
+<ul>
+<li><pre><code class="language-lang3">async text 3</code></pre>
+</li>
+</ul>
+`);
+      done();
+    });
+  });
 });
 
 describe('walkTokens', () => {