Auto merge of #15289 - montrivo:webidl-exposed, r=cbrewster

Expose interfaces only where they should be. #12415 - Partial

<!-- Please describe your changes on the following line: -->

I verified the following interfaces:
CSSStyleDeclaration.webidl
ElementCSSInlineStyle.webidl
ElementContentEditable.webidl
EventHandler.webidl
Screen.webidl
StyleSheetList.webidl
StyleSheet.webidl
Client.webidl

---
<!-- 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
- [ ] These changes fix #12415 (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/mozilla/tests/mozilla/interfaces.worker.js

@@ -9,7 +9,6 @@ importScripts("interfaces.js");
 test_interfaces([
   "Blob",
   "CloseEvent",
-  "CSSStyleDeclaration",
   "DOMMatrix",
   "DOMMatrixReadOnly",
   "DOMPoint",
@@ -38,7 +37,6 @@ test_interfaces([
   "ProgressEvent",
   "Request",
   "Response",
-  "Screen",
   "Storage",
   "StorageEvent",
   "TextDecoder",