servo: Merge #13167 - Replace current session entry when reloading (from cbrewster:reload_replace_current); r=asajeffrey

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This PR adds a replacement option when navigating. It replaces the current session history entry after a new page has been loaded. This will prevent reloading from adding a new entry to the session history.

---
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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 #13123 (github issue number if applicable).

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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Source-Repo: https://github.com/servo/servo
Source-Revision: 9876923b29ae7c4f2b763e368fc34fe8a051afc4

servo/components/script_traits/lib.rs

@@ -179,7 +179,7 @@ pub enum ConstellationControlMsg {
     NotifyVisibilityChange(PipelineId, PipelineId, bool),
     /// Notifies script thread that a url should be loaded in this iframe.
     /// First PipelineId is for the parent, second PipelineId is for the actual pipeline.
-    Navigate(PipelineId, PipelineId, LoadData),
+    Navigate(PipelineId, PipelineId, LoadData, bool),
     /// Requests the script thread forward a mozbrowser event to an iframe it owns,
     /// or to the window if no child pipeline id is provided.
     /// First PipelineId is for the parent, second PipelineId is for the actual pipeline.
@@ -459,6 +459,9 @@ pub struct IFrameLoadInfo {
     pub is_private: bool,
     /// Whether this iframe is a mozbrowser iframe
     pub frame_type: FrameType,
+    /// Wether this load should replace the current entry (reload). If true, the current
+    /// entry will be replaced instead of a new entry being added.
+    pub replace: bool,
 }
 
 // https://developer.mozilla.org/en-US/docs/Web/API/Using_the_Browser_API#Events