Auto merge of #12546 - malisas:malisa-bytestring-unions, r=KiChjang

Union types now allow ByteString

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This PR addresses issue #12527 to allow ByteStrings in union types.
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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 #12527  (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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components/script/dom/bindings/codegen/CodegenRust.py

@@ -2077,7 +2077,7 @@ def UnionTypes(descriptors, dictionaries, callbacks, config):
         'dom::bindings::conversions::root_from_handlevalue',
         'dom::bindings::error::throw_not_in_union',
         'dom::bindings::js::Root',
-        'dom::bindings::str::{DOMString, USVString}',
+        'dom::bindings::str::{ByteString, DOMString, USVString}',
         'dom::types::*',
         'js::jsapi::JSContext',
         'js::jsapi::{HandleValue, MutableHandleValue}',
@@ -3754,6 +3754,9 @@ def getUnionTypeTemplateVars(type, descriptorProvider):
         name = str(type)
         # XXXjdm dunno about typeName here
         typeName = "/*" + type.name + "*/"
+    elif type.isByteString():
+        name = type.name
+        typeName = "ByteString"
     elif type.isDOMString():
         name = type.name
         typeName = "DOMString"