LibJS: Include Environment.h directly in ClassFieldDefinition.h

This was previously indirectly forcing Heap/Handle.h to include it
instead. This will let us include Handle.h from PropertyKey, which will
allow us to solve a different issue.

Userland/Libraries/LibJS/Heap/Handle.h

@@ -12,7 +12,6 @@
 #include <AK/RefCounted.h>
 #include <AK/RefPtr.h>
 #include <LibJS/Forward.h>
-#include <LibJS/Runtime/Environment.h>
 #include <LibJS/Runtime/Value.h>
 
 namespace JS {

Userland/Libraries/LibJS/Runtime/ClassFieldDefinition.h

@@ -9,6 +9,7 @@
 #include <AK/Forward.h>
 #include <LibJS/Forward.h>
 #include <LibJS/Heap/Handle.h>
+#include <LibJS/Runtime/Environment.h>
 
 namespace JS {