Revert of Disable BrowserTest.InterstitialCloseTab which is flaky.

chrome/browser/ui/browser_browsertest.cc

Index: chrome/browser/ui/browser_browsertest.cc
diff --git a/chrome/browser/ui/browser_browsertest.cc b/chrome/browser/ui/browser_browsertest.cc
index 4e85b9d6d89b494d896120b6f40a226b399c04d4..d9a1b24c0f7070b178f11543119b916aa977c6be 100644
--- a/chrome/browser/ui/browser_browsertest.cc
+++ b/chrome/browser/ui/browser_browsertest.cc
@@ -1979,13 +1979,8 @@
   EXPECT_FALSE(contents->GetRenderProcessHost()->IgnoreInputEvents());
 }
 
-#if defined(OS_MACOSX)
-// http://crbug.com/393218
-#define MAYBE_InterstitialCloseTab DISABLED_InterstitialCloseTab
-#else
-#define MAYBE_InterstitialCloseTab InterstitialCloseTab
-#endif
-IN_PROC_BROWSER_TEST_F(BrowserTest, MAYBE_InterstitialCloseTab) {
+
+IN_PROC_BROWSER_TEST_F(BrowserTest, InterstitialCloseTab) {
   WebContents* contents = browser()->tab_strip_model()->GetActiveWebContents();
 
   {