Revert "spec: Suppress the test that destroys WebContents in event listener"

This reverts commit b315eb83fd.

spec/api-web-contents-spec.js

@@ -590,12 +590,6 @@ describe('webContents module', function () {
   })
 
   describe('destroy()', () => {
-    // Destroying webContents in its event listener is going to crash when
-    // Electron is built in Debug mode.
-    if (process.platform !== 'darwin') {
-      return
-    }
-
     let server
 
     before(function (done) {