servo: Merge #13485 - Make readystatechange fire more often (fixes #1…

…3481) (from mathieuh:xhr-event); r=jdm

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---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #13481 (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: d42235ee905acf6bea7f5983c77124b8be9656fc

UltraBlame original commit: a77c94d6a1d5906fe01a690c3a9564379239afff

servo/components/script/dom/xmlhttprequest.rs

@@ -7650,20 +7650,72 @@ HeadersReceived
 {
 self
 .
-change_ready_state
+ready_state
+.
+set
 (
 XMLHttpRequestState
 :
 :
 Loading
 )
 ;
+}
+let
+global
+=
+self
+.
+global
+(
+)
+;
+let
+event
+=
+Event
+:
+:
+new
+(
+global
+.
+r
+(
+)
+atom
+!
+(
+"
+readystatechange
+"
+)
+EventBubbles
+:
+:
+DoesNotBubble
+EventCancelable
+:
+:
+Cancelable
+)
+;
+event
+.
+fire
+(
+self
+.
+upcast
+(
+)
+)
+;
 return_if_fetch_was_terminated
 !
 (
 )
 ;
-}
 self
 .
 dispatch_response_progress_event