Introduce VirtualMethods::children_changed()

This virtual method mimics the behaviour of mutation observers and make it more
viable than the older child_inserted(), which didn't cover removed nodes and
was called as many times as there were inserted nodes.

A few other shortcomings where remove_child() was called directly instead of
Node::remove() were also fixed while at it.

components/script/dom/htmlscriptelement.rs

@@ -27,7 +27,8 @@ use dom::eventtarget::{EventTarget, EventTargetTypeId};
 use dom::event::{Event, EventBubbles, EventCancelable, EventHelpers};
 use dom::element::ElementTypeId;
 use dom::htmlelement::{HTMLElement, HTMLElementTypeId};
-use dom::node::{Node, NodeHelpers, NodeTypeId, document_from_node, window_from_node, CloneChildrenFlag};
+use dom::node::{ChildrenMutation, CloneChildrenFlag, Node, NodeHelpers};
+use dom::node::{NodeTypeId, document_from_node, window_from_node};
 use dom::servohtmlparser::ServoHTMLParserHelpers;
 use dom::virtualmethods::VirtualMethods;
 use dom::window::{WindowHelpers, ScriptHelpers};
@@ -564,9 +565,9 @@ impl<'a> VirtualMethods for &'a HTMLScriptElement {
         }
     }
 
-    fn child_inserted(&self, child: &Node) {
+    fn children_changed(&self, mutation: &ChildrenMutation) {
         if let Some(ref s) = self.super_type() {
-            s.child_inserted(child);
+            s.children_changed(mutation);
         }
         let node = NodeCast::from_ref(*self);
         if !self.parser_inserted.get() && node.is_in_doc() {

components/script/dom/htmlstyleelement.rs

@@ -11,7 +11,8 @@ use dom::document::Document;
 use dom::eventtarget::{EventTarget, EventTargetTypeId};
 use dom::element::{ElementTypeId, AttributeHandlers};
 use dom::htmlelement::{HTMLElement, HTMLElementTypeId};
-use dom::node::{Node, NodeHelpers, NodeTypeId, window_from_node};
+use dom::node::{ChildrenMutation, Node, NodeHelpers, NodeTypeId};
+use dom::node::window_from_node;
 use dom::virtualmethods::VirtualMethods;
 use dom::window::WindowHelpers;
 use layout_interface::{LayoutChan, Msg};
@@ -86,11 +87,10 @@ impl<'a> VirtualMethods for &'a HTMLStyleElement {
         Some(htmlelement as &VirtualMethods)
     }
 
-    fn child_inserted(&self, child: &Node) {
+    fn children_changed(&self, mutation: &ChildrenMutation) {
         if let Some(ref s) = self.super_type() {
-            s.child_inserted(child);
+            s.children_changed(mutation);
         }
-
         let node = NodeCast::from_ref(*self);
         if node.is_in_doc() {
             self.parse_own_css();

components/script/dom/htmltextareaelement.rs

@@ -11,7 +11,7 @@ use dom::bindings::codegen::Bindings::HTMLTextAreaElementBinding::HTMLTextAreaEl
 use dom::bindings::codegen::Bindings::NodeBinding::NodeMethods;
 use dom::bindings::codegen::InheritTypes::{ElementCast, EventTargetCast, HTMLElementCast, NodeCast};
 use dom::bindings::codegen::InheritTypes::{HTMLTextAreaElementDerived, HTMLFieldSetElementDerived};
-use dom::bindings::codegen::InheritTypes::{KeyboardEventCast, TextDerived};
+use dom::bindings::codegen::InheritTypes::KeyboardEventCast;
 use dom::bindings::global::GlobalRef;
 use dom::bindings::js::{LayoutJS, Root};
 use dom::bindings::refcounted::Trusted;
@@ -23,8 +23,8 @@ use dom::element::ElementTypeId;
 use dom::htmlelement::{HTMLElement, HTMLElementTypeId};
 use dom::htmlformelement::FormControl;
 use dom::keyboardevent::KeyboardEvent;
-use dom::node::{DisabledStateHelpers, Node, NodeHelpers, NodeDamage, NodeTypeId};
-use dom::node::{document_from_node, window_from_node};
+use dom::node::{ChildrenMutation, DisabledStateHelpers, Node, NodeDamage};
+use dom::node::{NodeHelpers, NodeTypeId, document_from_node, window_from_node};
 use textinput::{TextInput, Lines, KeyReaction};
 use dom::virtualmethods::VirtualMethods;
 use dom::window::WindowHelpers;
@@ -330,12 +330,11 @@ impl<'a> VirtualMethods for &'a HTMLTextAreaElement {
         }
     }
 
-    fn child_inserted(&self, child: &Node) {
-        if let Some(s) = self.super_type() {
-            s.child_inserted(child);
+    fn children_changed(&self, mutation: &ChildrenMutation) {
+        if let Some(ref s) = self.super_type() {
+            s.children_changed(mutation);
         }
-
-        if child.is_text() && !self.value_changed.get() {
+        if !self.value_changed.get() {
             self.reset();
         }
     }

components/script/dom/htmltitleelement.rs

@@ -13,7 +13,7 @@ use dom::document::{Document, DocumentHelpers};
 use dom::eventtarget::{EventTarget, EventTargetTypeId};
 use dom::element::ElementTypeId;
 use dom::htmlelement::{HTMLElement, HTMLElementTypeId};
-use dom::node::{Node, NodeHelpers, NodeTypeId};
+use dom::node::{ChildrenMutation, Node, NodeHelpers, NodeTypeId};
 use dom::text::Text;
 use dom::virtualmethods::VirtualMethods;
 use util::str::DOMString;
@@ -75,15 +75,13 @@ impl<'a> VirtualMethods for &'a HTMLTitleElement {
         Some(htmlelement as &VirtualMethods)
     }
 
-    fn child_inserted(&self, child: &Node) {
+    fn children_changed(&self, mutation: &ChildrenMutation) {
         if let Some(ref s) = self.super_type() {
-            s.child_inserted(child);
+            s.children_changed(mutation);
         }
-
         let node = NodeCast::from_ref(*self);
         if node.is_in_doc() {
-            let document = node.owner_doc();
-            document.r().title_changed();
+            node.owner_doc().title_changed();
         }
     }