Add DocumentFragment getElementById

src/browser/dom/document_fragment.zig

@@ -83,6 +83,11 @@ pub const DocumentFragment = struct {
             .include_root = false,
         });
     }
+
+    pub fn _getElementById(self: *parser.DocumentFragment, id: []const u8) !?ElementUnion {
+        const e = try parser.nodeGetElementById(@alignCast(@ptrCast(self)), id) orelse return null;
+        return try Element.toInterface(e);
+    }
 };
 
 const testing = @import("../../testing.zig");

src/browser/dom/shadow_root.zig

@@ -44,7 +44,9 @@ const testing = @import("../../testing.zig");
 test "Browser.DOM.ShadowRoot" {
     defer testing.reset();
 
-    var runner = try testing.jsRunner(testing.tracking_allocator, .{ .html = "" });
+    var runner = try testing.jsRunner(testing.tracking_allocator, .{ .html =
+        \\ <div id=conflict>nope</div>
+    });
     defer runner.deinit();
 
     try runner.testCases(&.{
@@ -70,4 +72,12 @@ test "Browser.DOM.ShadowRoot" {
         .{ "sr2.host == div2", "true" },
         .{ "div2.shadowRoot", "null" }, // null when attached with 'closed'
     }, .{});
+
+    try runner.testCases(&.{
+        .{ "sr2.getElementById('conflict')", "null" },
+        .{ "const n1 = document.createElement('div')", null },
+        .{ "n1.id = 'conflict'", null},
+        .{ "sr2.append(n1)", null},
+        .{ "sr2.getElementById('conflict') == n1", "true" },
+    }, .{});
 }

src/browser/netsurf.zig

@@ -1418,6 +1418,13 @@ pub fn nodeSetEmbedderData(node: *Node, data: *anyopaque) void {
     c._dom_node_set_embedder_data(node, data);
 }
 
+pub fn nodeGetElementById(node: *Node, id: []const u8) !?*Element {
+    var el: ?*Element = undefined;
+    const str_id = try strFromData(id);
+    try DOMErr(c._dom_find_element_by_id(node, str_id, &el));
+    return el;
+}
+
 // nodeToElement is an helper to convert a node to an element.
 pub inline fn nodeToElement(node: *Node) *Element {
     return @as(*Element, @ptrCast(node));