Setting innerHTML now captures head elements

I couldn't find where the behavior is described. AND, browsers seem to behave
differently depending on the state of the page (blank document vs actual page).

Still, some sites use innerHTML to load <script> tags, and, in libdom at least,
these are created in the implicit head. We cannot just copy the body nodes. To
keep it simple, I now copy all head and body elements.

Author: karlseguin

src/browser/dom/element.zig

@@ -127,16 +127,40 @@ pub const Element = struct {
         // remove existing children
         try Node.removeChildren(node);
 
-        // get fragment body children
-        const children = try parser.documentFragmentBodyChildren(fragment) orelse return;
-
-        // append children to the node
-        const ln = try parser.nodeListLength(children);
-        for (0..ln) |_| {
-            // always index 0, because ndoeAppendChild moves the node out of
-            // the nodeList and into the new tree
-            const child = try parser.nodeListItem(children, 0) orelse continue;
-            _ = try parser.nodeAppendChild(node, child);
+        // I'm not sure what the exact behavior is supposed to be. Initially,
+        // we were only copying the body of the document fragment. But it seems
+        // like head elements should be copied too. Specifically, some sites
+        // create script tags via innerHTML, which we need to capture.
+        // If you play with this in a browser, you should notice that the
+        // behavior is different depending on whether you're in a blank page
+        // or an actual document. In a blank page, something like:
+        //    x.innerHTML = '<script></script>';
+        // does _not_ create an empty script, but in a real page, it does. Weird.
+        const fragment_node = parser.documentFragmentToNode(fragment);
+        const html = try parser.nodeFirstChild(fragment_node) orelse return;
+        const head = try parser.nodeFirstChild(html) orelse return;
+        {
+            // First, copy some of the head element
+            const children = try parser.nodeGetChildNodes(head);
+            const ln = try parser.nodeListLength(children);
+            for (0..ln) |_| {
+                // always index 0, because nodeAppendChild moves the node out of
+                // the nodeList and into the new tree
+                const child = try parser.nodeListItem(children, 0) orelse continue;
+                _ = try parser.nodeAppendChild(node, child);
+            }
+        }
+
+        {
+            const body = try parser.nodeNextSibling(head) orelse return;
+            const children = try parser.nodeGetChildNodes(body);
+            const ln = try parser.nodeListLength(children);
+            for (0..ln) |_| {
+                // always index 0, because nodeAppendChild moves the node out of
+                // the nodeList and into the new tree
+                const child = try parser.nodeListItem(children, 0) orelse continue;
+                _ = try parser.nodeAppendChild(node, child);
+            }
         }
     }
 
@@ -688,5 +712,10 @@ test "Browser.DOM.Element" {
 
     try runner.testCases(&.{
         .{ "document.createElement('a').hasAttributes()", "false" },
+        .{ "var fc; (fc = document.createElement('div')).innerHTML = '<script><\\/script>'", null },
+        .{ "fc.outerHTML", "<div><script></script></div>" },
+
+        .{ "fc; (fc = document.createElement('div')).innerHTML = '<script><\\/script><p>hello</p>'", null },
+        .{ "fc.outerHTML", "<div><script></script><p>hello</p></div>" },
     }, .{});
 }

src/browser/netsurf.zig

@@ -1925,18 +1925,6 @@ pub inline fn documentFragmentToNode(doc: *DocumentFragment) *Node {
     return @as(*Node, @alignCast(@ptrCast(doc)));
 }
 
-pub fn documentFragmentBodyChildren(doc: *DocumentFragment) !?*NodeList {
-    const node = documentFragmentToNode(doc);
-    const html = try nodeFirstChild(node) orelse return null;
-    // TODO unref
-    const head = try nodeFirstChild(html) orelse return null;
-    // TODO unref
-    const body = try nodeNextSibling(head) orelse return null;
-    // TODO unref
-
-    return try nodeGetChildNodes(body);
-}
-
 // Document Position
 
 pub const DocumentPosition = enum(u32) {