codegen: Implement WebIDL sequence arguments

components/script/dom/bindings/codegen/CodegenRust.py

@@ -700,7 +700,16 @@ def getJSToNativeConversionInfo(type, descriptorProvider, failureCode=None,
         raise TypeError("Can't handle array arguments yet")
 
     if type.isSequence():
-        raise TypeError("Can't handle sequence arguments yet")
+        # Use the same type that for return values
+        declType = getRetvalDeclarationForType(type, descriptorProvider)
+        config = getConversionConfigForType(type, isEnforceRange, isClamp, treatNullAs)
+
+        templateBody = ("match FromJSValConvertible::from_jsval(cx, ${val}, %s) {\n"
+                        "    Ok(value) => value,\n"
+                        "    Err(()) => { %s },\n"
+                        "}" % (config, exceptionCode))
+
+        return handleOptional(templateBody, declType, handleDefaultNull("None"))
 
     if type.isUnion():
         declType = CGGeneric(union_native_type(type))

components/util/non_geckolib.rs

@@ -25,7 +25,7 @@ use std::slice;
 use str::DOMString;
 
 /// Behavior for stringification of `JSVal`s.
-#[derive(PartialEq)]
+#[derive(PartialEq, Clone)]
 pub enum StringificationBehavior {
     /// Convert `null` to the string `"null"`.
     Default,