Auto merge of #16238 - gterzian:implement_update_the_image_data, r=jdm

Implement "update the image data"

<!-- Please describe your changes on the following line: -->
Spec compliant implementation of the [update the image data algorithm](https://html.spec.whatwg.org/multipage/embedded-content.html#update-the-image-data).

Currently still a work in progress, the ['async src complete test`](https://github.com/servo/servo/blob/master/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/img.complete.html#L33) is still passing as it was before, even though I switched to the new code, so I guess that's something.

@jdm I will be picking this up next weekend, I left a bunch of TODO and NOTES in the code, if you or someone else have time this week I would appreciate an initial scan and feedback.

---
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- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #11517 (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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tests/wpt/metadata/MANIFEST.json

@@ -571006,7 +571006,7 @@
    "support"
   ],
   "html/semantics/embedded-content/the-img-element/img.complete.html": [
-   "723ded8aca956dc1f3cbc60feb0e502c2b943d1d",
+   "be6ea10ac070420948bcef0372c283f275a6b00f",
    "testharness"
   ],
   "html/semantics/embedded-content/the-img-element/invalid-src.html": [

tests/wpt/metadata/html/semantics/embedded-content/the-img-element/img.complete.html.ini

@@ -1,14 +1,5 @@
 [img.complete.html]
   type: testharness
-  [img src omitted]
-    expected: FAIL
-
-  [img src empty]
-    expected: FAIL
-
   [IDL attribute complete returns true when image resource has been fetched but not run yet & image is not in broken state]
     expected: FAIL
 
-  [async src broken test]
-    expected: FAIL
-

tests/wpt/metadata/html/semantics/embedded-content/the-img-element/update-src-complete.html.ini

@@ -1,5 +0,0 @@
-[update-src-complete.html]
-  type: testharness
-  [Changing the img src should retain the 'complete' property]
-    expected: FAIL
-