LibWeb: Add partial support for IDL Iterable declarations

This currently only supports pair iterables (i.e. iterable<key, value>)
support for value iterables (i.e. iterable<value>) is left as TODO().

Since currently our cmake setup calls the WrapperGenerator separately
and unconditionally for each (hard-coded) output file iterable wrappers
have to be explicitly marked so in the CMakeLists.txt declaration, we
could likely improve this in the future by querying WrapperGenerator
for the outputs based on the IDL.

Userland/Libraries/LibWeb/CMakeLists.txt

@@ -271,6 +271,7 @@ serenity_lib(LibWeb web)
 target_link_libraries(LibWeb LibCore LibJS LibMarkdown LibGemini LibGUI LibGfx LibTextCodec LibProtocol LibImageDecoderClient LibWasm)
 
 function(libweb_js_wrapper class)
+    cmake_parse_arguments(PARSE_ARGV 1 LIBWEB_WRAPPER "ITERABLE" "" "")
     get_filename_component(basename "${class}" NAME)
     set(BINDINGS_SOURCES
         "Bindings/${basename}Wrapper.h"
@@ -288,6 +289,21 @@ function(libweb_js_wrapper class)
         prototype-header
         prototype-implementation
     )
+    # FIXME: Instead of requiring a manual declaration of iterable wrappers, we should ask WrapperGenerator if it's iterable
+    if(LIBWEB_WRAPPER_ITERABLE)
+        list(APPEND BINDINGS_SOURCES
+            "Bindings/${basename}IteratorWrapper.h"
+            "Bindings/${basename}IteratorWrapper.cpp"
+            "Bindings/${basename}IteratorPrototype.h"
+            "Bindings/${basename}IteratorPrototype.cpp"
+        )
+        list(APPEND BINDINGS_TYPES
+            iterator-header
+            iterator-implementation
+            iterator-prototype-header
+            iterator-prototype-implementation
+        )
+    endif()
     target_sources(LibWeb PRIVATE ${BINDINGS_SOURCES})
     # FIXME: cmake_minimum_required(3.17) for ZIP_LISTS
     list(LENGTH BINDINGS_SOURCES num_bindings)