Remove the script listener thread (fixes #11345).

We needed a separate thread in the chrome process because communication to the
compositor is done through a trait object, and cross-process virtual calls are
forbidden.

Also, the fact that these messages are ultimately handled by the compositor is
an implementation detail; conceptually, the relevant constellation is supposed
to handle these messages.

So instead, the script thread will now send the messages to the constellation,
which will ask the compositor to handle them.

components/script_traits/script_msg.rs

@@ -11,9 +11,10 @@ use MozBrowserEvent;
 use canvas_traits::CanvasMsg;
 use euclid::point::Point2D;
 use euclid::size::Size2D;
+use gfx_traits::LayerId;
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::{LoadData, SubpageId};
-use msg::constellation_msg::{NavigationDirection, PipelineId};
+use msg::constellation_msg::{Key, KeyModifiers, KeyState, LoadData};
+use msg::constellation_msg::{NavigationDirection, PipelineId, SubpageId};
 use offscreen_gl_context::{GLContextAttributes, GLLimits};
 use style_traits::cursor::Cursor;
 use style_traits::viewport::ViewportConstraints;
@@ -30,6 +31,15 @@ pub enum LayoutMsg {
     ViewportConstrained(PipelineId, ViewportConstraints),
 }
 
+/// Whether a DOM event was prevented by web content
+#[derive(Deserialize, Serialize)]
+pub enum EventResult {
+    /// Allowed by web content
+    DefaultAllowed,
+    /// Prevented by web content
+    DefaultPrevented,
+}
+
 /// Messages from the script to the constellation.
 #[derive(Deserialize, Serialize)]
 pub enum ScriptMsg {
@@ -83,4 +93,23 @@ pub enum ScriptMsg {
     SetFinalUrl(PipelineId, Url),
     /// Check if an alert dialog box should be presented
     Alert(PipelineId, String, IpcSender<bool>),
+    /// Scroll a page in a window
+    ScrollFragmentPoint(PipelineId, LayerId, Point2D<f32>, bool),
+    /// Set title of current page
+    /// https://html.spec.whatwg.org/multipage/#document.title
+    SetTitle(PipelineId, Option<String>),
+    /// Send a key event
+    SendKeyEvent(Key, KeyState, KeyModifiers),
+    /// Get Window Informations size and position
+    GetClientWindow(IpcSender<(Size2D<u32>, Point2D<i32>)>),
+    /// Move the window to a point
+    MoveTo(Point2D<i32>),
+    /// Resize the window to size
+    ResizeTo(Size2D<u32>),
+    /// Script has handled a touch event, and either prevented or allowed default actions.
+    TouchEventProcessed(EventResult),
+    /// Get Scroll Offset
+    GetScrollOffset(PipelineId, LayerId, IpcSender<Point2D<f32>>),
+    /// Requests that the compositor shut down.
+    Exit,
 }