Bug 1649974 - P1. Make WeakPtr work with generic taskqueue. r=froydnj

It worked until now as IPC's MessageChannel was only used with background taskqueue; which use a threadpool made of a single thread only.

Differential Revision: https://phabricator.services.mozilla.com/D82499

js/src/devtools/rootAnalysis/annotations.js

@@ -295,6 +295,10 @@ var ignoreFunctions = {
 
     // Calls MergeSort
     "uint8 v8::internal::RegExpDisjunction::SortConsecutiveAtoms(v8::internal::RegExpCompiler*)": true,
+
+    // nsIEventTarget.IsOnCurrentThreadInfallible does not get resolved, and
+    // this is called on non-JS threads so cannot use AutoSuppressGCAnalysis.
+    "uint8 nsAutoOwningEventTarget::IsCurrentThread() const": true,
 };
 
 function extraGCFunctions() {

mfbt/WeakPtr.h

@@ -98,12 +98,12 @@
 // on a single thread.  The following macros implement assertions for
 // checking these conditions.
 //
-// We re-use XPCOM's nsAutoOwningThread checks when they are available. This has
-// the advantage that it works with cooperative thread pools.
+// We re-use XPCOM's nsAutoOwningEventTarget checks when they are available.
+// This has the advantage that it works with cooperative thread pools.
 
 #  define MOZ_WEAKPTR_DECLARE_THREAD_SAFETY_CHECK \
     /* Will be none if mPtr = nullptr. */         \
-    Maybe<nsAutoOwningThread> _owningThread;
+    Maybe<nsAutoOwningEventTarget> _owningThread;
 #  define MOZ_WEAKPTR_INIT_THREAD_SAFETY_CHECK() \
     do {                                         \
       if (p) {                                   \