docs(testing): delete extra 'with' (#2513)

Deleted extra 'with'

Author: Belax8

public/docs/ts/latest/guide/testing.jade

@@ -408,7 +408,7 @@ a(href="#top").to-top Back to top
 +makeExample('testing/ts/app/banner.component.spec.ts', 'simple-example-it', 'app/banner.component.spec.ts (simplified)')(format='.')
 :marked
   A comprehensive review of the Angular testing utilities appears [later in the chapter](#atu-apis).
-  Let's dive right into Angular testing, starting with with the components of a sample application.
+  Let's dive right into Angular testing, starting with the components of a sample application.
 
 a(href="#top").to-top Back to top