Auto merge of #15129 - cynicaldevil:iframe-resize, r=emilio

Refactor to send iframe resize messages directly from layout thread to constellation

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #14682.
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r? @jdm
passing tests:
tests/wpt/mozilla/tests/css/matchMedia.html, tests/wpt/mozilla/tests/mozilla/window_resize_not_triggered_on_load.html, tests/wpt/mozilla/tests/mozilla/iframe/resize_after_load.html, tests/wpt/mozilla/tests/css/meta_viewport_resize.html

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components/script_traits/lib.rs

@@ -696,8 +696,6 @@ pub enum WebDriverCommandMsg {
 pub enum ConstellationMsg {
     /// Exit the constellation.
     Exit,
-    /// Inform the constellation of the size of the viewport.
-    FrameSize(PipelineId, Size2D<f32>),
     /// Request that the constellation send the FrameId corresponding to the document
     /// with the provided pipeline id
     GetFrame(PipelineId, IpcSender<Option<FrameId>>),

components/script_traits/script_msg.rs

@@ -15,7 +15,7 @@ use WorkerScriptLoadOrigin;
 use canvas_traits::CanvasMsg;
 use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
 use euclid::point::Point2D;
-use euclid::size::Size2D;
+use euclid::size::{Size2D, TypedSize2D};
 use gfx_traits::ScrollRootId;
 use ipc_channel::ipc::IpcSender;
 use msg::constellation_msg::{FrameId, PipelineId, TraversalDirection};
@@ -24,6 +24,7 @@ use net_traits::CoreResourceMsg;
 use net_traits::storage_thread::StorageType;
 use offscreen_gl_context::{GLContextAttributes, GLLimits};
 use servo_url::ServoUrl;
+use style_traits::PagePx;
 use style_traits::cursor::Cursor;
 use style_traits::viewport::ViewportConstraints;
 
@@ -32,6 +33,8 @@ use style_traits::viewport::ViewportConstraints;
 pub enum LayoutMsg {
     /// Indicates whether this pipeline is currently running animations.
     ChangeRunningAnimationsState(PipelineId, AnimationState),
+    /// Inform the constellation of the size of the pipeline's viewport.
+    FrameSizes(Vec<(PipelineId, TypedSize2D<f32, PagePx>)>),
     /// Requests that the constellation inform the compositor of the a cursor change.
     SetCursor(Cursor),
     /// Notifies the constellation that the viewport has been constrained in some manner