Auto merge of #23816 - marmeladema:issue-20377, r=jdm

Wrapping unsafe raw JSContext pointers in a safe struct. Part 1.

Wrapping unsafe raw JSContext pointers in a safe struct. Issue #20377.

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<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] create a struct JSContext(*mut jsapi::JSContext) type
- [x] implement Deref for this new type so it's easy to obtain the inner context pointer
- [x] add an unsafe from_ptr static method that returns a new instance of the type
- [x] start by changing various Argument uses in CodegenRust.py for python classes that inherit from CGAbstractMethod
- [x] convert the python code that interacts with CGClass (CGCallback, CGCallbackFunction, CGCallbackFunctionImpl, CGCallbackInterface) and any rust code that interacts with it
- [x] update CGDictionary and any rust code that interacts with it
- [x] make the code generator declare trait methods that accept the new type instead of *mut JSContext (CGInterfaceTrait)
- [x] modify GlobalScope::get_cx to return a SafeJSContext

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<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

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1 files changed, 6 insertions, 5 deletions

diff --git a/components/script/dom/crypto.rs b/components/script/dom/crypto.rs
index 76adb3a08b1..4891c022ed5 100644
--- a/components/script/dom/crypto.rs
+++ b/components/script/dom/crypto.rs
@@ -9,9 +9,10 @@ use crate::dom::bindings::error::{Error, Fallible};
 use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
 use crate::dom::bindings::root::DomRoot;
 use crate::dom::globalscope::GlobalScope;
+use crate::script_runtime::JSContext;
 use dom_struct::dom_struct;
+use js::jsapi::JSObject;
 use js::jsapi::Type;
-use js::jsapi::{JSContext, JSObject};
 use js::rust::CustomAutoRooterGuard;
 use js::typedarray::ArrayBufferView;
 use servo_rand::{Rng, ServoRng};
@@ -47,9 +48,9 @@ impl Crypto {
 impl CryptoMethods for Crypto {
     #[allow(unsafe_code)]
     // https://dvcs.w3.org/hg/webcrypto-api/raw-file/tip/spec/Overview.html#Crypto-method-getRandomValues
-    unsafe fn GetRandomValues(
+    fn GetRandomValues(
         &self,
-        _cx: *mut JSContext,
+        _cx: JSContext,
         mut input: CustomAutoRooterGuard<ArrayBufferView>,
     ) -> Fallible<NonNull<JSObject>> {
         let array_type = input.get_array_type();
@@ -57,14 +58,14 @@ impl CryptoMethods for Crypto {
         if !is_integer_buffer(array_type) {
             return Err(Error::TypeMismatch);
         } else {
-            let mut data = input.as_mut_slice();
+            let mut data = unsafe { input.as_mut_slice() };
             if data.len() > 65536 {
                 return Err(Error::QuotaExceeded);
             }
             self.rng.borrow_mut().fill_bytes(&mut data);
         }
 
-        Ok(NonNull::new_unchecked(*input.underlying_object()))
+        unsafe { Ok(NonNull::new_unchecked(*input.underlying_object())) }
     }
 }