4 files changed, 19 insertions, 10 deletions
diff --git a/components/script/dom/dedicatedworkerglobalscope.rs b/components/script/dom/dedicatedworkerglobalscope.rs
index 8373855ac14..d02c57845ea 100644
--- a/components/script/dom/dedicatedworkerglobalscope.rs
+++ b/components/script/dom/dedicatedworkerglobalscope.rs
@@ -213,7 +213,8 @@ impl DedicatedWorkerGlobalScope {
                             worker_url: Url,
                             id: PipelineId,
                             from_devtools_receiver: IpcReceiver<DevtoolScriptControlMsg>,
-                            main_thread_rt: Arc<Mutex<Option<SharedRt>>>,
+                            parent_rt: SharedRt,
+                            worker_rt_for_mainthread: Arc<Mutex<Option<SharedRt>>>,
                             worker: TrustedWorkerAddress,
                             parent_sender: Box<ScriptChan + Send>,
                             own_sender: Sender<(TrustedWorkerAddress, WorkerScriptMsg)>,
@@ -240,8 +241,8 @@ impl DedicatedWorkerGlobalScope {
                 }
             };
 
-            let runtime = unsafe { new_rt_and_cx() };
-            *main_thread_rt.lock().unwrap() = Some(SharedRt::new(&runtime));
+            let runtime = unsafe { new_rt_and_cx(parent_rt.rt()) };
+            *worker_rt_for_mainthread.lock().unwrap() = Some(SharedRt::new(&runtime));
 
             let (devtools_mpsc_chan, devtools_mpsc_port) = channel();
             ROUTER.route_ipc_receiver_to_mpsc_sender(from_devtools_receiver, devtools_mpsc_chan);
diff --git a/components/script/dom/worker.rs b/components/script/dom/worker.rs
index e969328a210..0a18125f1bc 100644
--- a/components/script/dom/worker.rs
+++ b/components/script/dom/worker.rs
@@ -22,7 +22,7 @@ use dom::messageevent::MessageEvent;
 use dom::workerglobalscope::WorkerGlobalScopeInit;
 use ipc_channel::ipc;
 use js::jsapi::{HandleValue, JSContext, JSRuntime, RootedValue};
-use js::jsapi::{JSAutoCompartment, JS_RequestInterruptCallback};
+use js::jsapi::{JSAutoCompartment, JS_GetRuntime, JS_RequestInterruptCallback};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
 use msg::constellation_msg::{PipelineId, ReferrerPolicy};
@@ -91,6 +91,7 @@ impl Worker {
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-worker
+    #[allow(unsafe_code)]
     pub fn Constructor(global: GlobalRef, script_url: DOMString) -> Fallible<Root<Worker>> {
         // Step 2-4.
         let worker_url = match global.api_base_url().join(&script_url) {
@@ -145,8 +146,10 @@ impl Worker {
             closing: closing,
         };
 
+        let shared_rt = SharedRt { rt: unsafe { JS_GetRuntime(global.get_cx()) } };
+
         DedicatedWorkerGlobalScope::run_worker_scope(
-            init, worker_url, global.pipeline(), devtools_receiver, worker.runtime.clone(), worker_ref,
+            init, worker_url, global.pipeline(), devtools_receiver, shared_rt, worker.runtime.clone(), worker_ref,
             global.script_chan(), sender, receiver, worker_load_origin);
 
         Ok(worker)
@@ -309,6 +312,10 @@ impl SharedRt {
             JS_RequestInterruptCallback(self.rt);
         }
     }
+
+    pub fn rt(&self) -> *mut JSRuntime {
+        self.rt
+    }
 }
 
 #[allow(unsafe_code)]
diff --git a/components/script/script_runtime.rs b/components/script/script_runtime.rs
index 543574ccc62..2b2e2437e16 100644
--- a/components/script/script_runtime.rs
+++ b/components/script/script_runtime.rs
@@ -95,9 +95,9 @@ impl<'a> Drop for StackRootTLS<'a> {
 }
 
 #[allow(unsafe_code)]
-pub unsafe fn new_rt_and_cx() -> Runtime {
+pub unsafe fn new_rt_and_cx(parent_rt: *mut JSRuntime) -> Runtime {
     LiveDOMReferences::initialize();
-    let runtime = Runtime::new();
+    let runtime = Runtime::new(parent_rt);
 
     JS_AddExtraGCRootsTracer(runtime.rt(), Some(trace_rust_roots), ptr::null_mut());
     JS_AddExtraGCRootsTracer(runtime.rt(), Some(trace_refcounted_objects), ptr::null_mut());
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 24172ab900f..8b87dcb2169 100644
--- a/components/script/script_thread.rs
+++ b/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(),