Meta/gn: Don't use "abspath" for IDL inputs

The idl file lists are used for two things:

1. As inputs for `generate_window_or_worker_interfaces`
2. In a loop in `generate_idl_bindings` and the loop variable
   is passed to `rebase_path`

Both these cases can handle a normal fully-qualified GN path,
so there's no need for the "abspath".

No behavior change.

Meta/gn/secondary/Userland/Libraries/LibWeb/generate_idl_bindings.gni

@@ -12,19 +12,16 @@
 # Parameters:
 #   idl_list (required) [string]
 #     List of IDL files that are all the same type.
-#     Expected to be an absolute path.
 #
 #   type (required) string
 #       "global", "iterable", "namespace", or "standard"
 #
 # Example use:
 #
-#  standard_idl_files = get_path_info(
-#    [
+#  standard_idl_files = [
 #    "//Library/Foo.idl",
 #    "//Bar.idl"
-#    ],
-#    "abspath")
+#  ]
 #
 #  generate_idl_bindings("standard_idl_bindings") {
 #    idl_list = standard_idl_files

Meta/gn/secondary/Userland/Libraries/LibWeb/idl_files.gni

@@ -4,27 +4,21 @@
 # Most IDL files are going to be "standard".
 #
 
-iterable_idl_files =
-    get_path_info([
+iterable_idl_files = [
   "//Userland/Libraries/LibWeb/Fetch/Headers.idl",
   "//Userland/Libraries/LibWeb/URL/URLSearchParams.idl",
   "//Userland/Libraries/LibWeb/XHR/FormData.idl",
-                  ],
-                  "abspath")
+]
 
-namespace_idl_files =
-    get_path_info([
+namespace_idl_files = [
   "//Userland/Libraries/LibWeb/CSS/CSS.idl",
   "//Userland/Libraries/LibWeb/WebAssembly/WebAssembly.idl",
-                  ],
-                  "abspath")
+]
 
-global_idl_files =
-    get_path_info([ "//Userland/Libraries/LibWeb/HTML/Window.idl" ], "abspath")
+global_idl_files = [ "//Userland/Libraries/LibWeb/HTML/Window.idl" ]
 
 # Standard idl files are neither iterable, namespaces, or global
-standard_idl_files = get_path_info(
-        [
+standard_idl_files = [
   "//Userland/Libraries/LibWeb/Crypto/Crypto.idl",
   "//Userland/Libraries/LibWeb/Crypto/SubtleCrypto.idl",
   "//Userland/Libraries/LibWeb/CSS/CSSConditionRule.idl",
@@ -269,5 +263,4 @@ standard_idl_files = get_path_info(
   "//Userland/Libraries/LibWeb/XHR/XMLHttpRequest.idl",
   "//Userland/Libraries/LibWeb/XHR/XMLHttpRequestEventTarget.idl",
   "//Userland/Libraries/LibWeb/XHR/XMLHttpRequestUpload.idl",
-        ],
-        "abspath")
+]