Auto merge of #11791 - craftytrickster:11712/pipeline-lookup, r=asajeffrey

Pipeline lookup in webdriver

Fixes #11712

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Removed a method that seemed to duplicate already existing functionality, and returned BrowsingContextErrors in the web_handler file where panics were previously occurring.

I am not sure if I like all the unwrapping that occurs in the script thread, but the current methods are not set up to return Option/Result.

Also, should line the method on line 37 `find_node_by_unique_id` of components/script/webdriver_handlers.rs return None if the context is not found like I have it currently? Or should it return a `Result<Option...>` instead?

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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 #11712 .

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because I simply removed a method that duplicated already existing functionality. On the other part, I added better error sending instead of forcing a panic, which does not require testing to my knowledge.

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components/script_traits/webdriver_msg.rs

@@ -53,7 +53,10 @@ pub enum WebDriverJSValue {
 #[derive(Deserialize, Serialize)]
 pub enum WebDriverJSError {
     Timeout,
-    UnknownType
+    UnknownType,
+    /// Occurs when handler received an event message for a layout channel that is not
+    /// associated with the current script thread
+    BrowsingContextNotFound
 }
 
 pub type WebDriverJSResult = Result<WebDriverJSValue, WebDriverJSError>;