Auto merge of #11372 - tschneidereit:parent-js-runtime-for-workers, r=nox

Pass a parent JS runtime when creating DOM Worker runtimes

This enables sharing data with the parent runtime, decreasing memory usage and startup time. Also contains an update to current rust-mozjs, because that's required for this to work.

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy --faster` does not report any errors
- [x] These changes don't fix a github issue

Either:
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because the changes don't change any observable behavior

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components/script/script_thread.rs

@@ -87,6 +87,7 @@ use std::borrow::ToOwned;
 use std::cell::{Cell, RefCell};
 use std::collections::HashSet;
 use std::option::Option;
+use std::ptr;
 use std::rc::Rc;
 use std::result::Result;
 use std::sync::atomic::{Ordering, AtomicBool};
@@ -443,8 +444,8 @@ impl ScriptThreadFactory for ScriptThread {
             let mem_profiler_chan = state.mem_profiler_chan.clone();
             let window_size = state.window_size;
             let script_thread = ScriptThread::new(state,
-                                              script_port,
-                                              script_chan.clone());
+                                                  script_port,
+                                                  script_chan.clone());
 
             SCRIPT_THREAD_ROOT.with(|root| {
                 *root.borrow_mut() = Some(&script_thread as *const _);
@@ -519,7 +520,7 @@ impl ScriptThread {
                port: Receiver<MainThreadScriptMsg>,
                chan: Sender<MainThreadScriptMsg>)
                -> ScriptThread {
-        let runtime = unsafe { new_rt_and_cx() };
+        let runtime = unsafe { new_rt_and_cx(ptr::null_mut()) };
 
         unsafe {
             JS_SetWrapObjectCallbacks(runtime.rt(),