Everywhere: Remove unused includes of AK/IterationDecision.h

These instances were detected by searching for files that include
IterationDecision.h, but don't match the regex:
\\bIterationDecision(?!\.h>)\\b
This is the only symbol defined by IterationDecision.h.

In theory, one might use LibCPP to detect things like this
automatically, but let's do this one step after another.

AK/Types.h

@@ -6,7 +6,6 @@
 
 #pragma once
 
-#include <AK/IterationDecision.h>
 #include <AK/Platform.h>
 #include <AK/StdLibExtras.h>
 

Userland/Applications/Browser/main.cpp

@@ -6,7 +6,6 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/IterationDecision.h>
 #include <Applications/Browser/Browser.h>
 #include <Applications/Browser/BrowserWindow.h>
 #include <Applications/Browser/CookieJar.h>

Userland/Libraries/LibGUI/GML/AST.h

@@ -11,7 +11,6 @@
 #include <AK/Error.h>
 #include <AK/Forward.h>
 #include <AK/HashMap.h>
-#include <AK/IterationDecision.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonValue.h>
 #include <AK/NonnullRefPtr.h>