[JSC] Early return in microtask draining when termination happens

https://bugs.webkit.org/show_bug.cgi?id=257163
rdar://109401883

Reviewed by Mark Lam.

This is Debug only, JSC shell only issue. Early returning from microtask draining when termination happens.

* JSTests/stress/exception-check-unhandled-promise-rejection-in-shell.js: Added.
(async foo):
* Source/JavaScriptCore/runtime/VM.cpp:
(JSC::VM::didExhaustMicrotaskQueue):
(JSC::VM::drainMicrotasks):

Canonical link: https://commits.webkit.org/264390@main

Author: Constellation

JSTests/stress/exception-check-unhandled-promise-rejection-in-shell.js

@@ -0,0 +1,9 @@
+//@ runDefault("--watchdog=100", "--watchdog-exception-ok")
+async function foo() {
+  await undefined;
+  throw new Error();
+}
+
+setUnhandledRejectionCallback(foo);
+foo();
+drainMicrotasks();

Source/JavaScriptCore/runtime/VM.cpp

@@ -1240,6 +1240,8 @@ void VM::didExhaustMicrotaskQueue()
                 continue;
 
             callPromiseRejectionCallback(promise);
+            if (UNLIKELY(hasPendingTerminationException()))
+                return;
         }
     } while (!m_aboutToBeNotifiedRejectedPromises.isEmpty());
 }
@@ -1258,10 +1260,14 @@ void VM::drainMicrotasks()
             while (!m_microtaskQueue.isEmpty()) {
                 auto task = m_microtaskQueue.dequeue();
                 task.run();
+                if (UNLIKELY(hasPendingTerminationException()))
+                    return;
                 if (m_onEachMicrotaskTick)
                     m_onEachMicrotaskTick(*this);
             }
             didExhaustMicrotaskQueue();
+            if (UNLIKELY(hasPendingTerminationException()))
+                return;
         } while (!m_microtaskQueue.isEmpty());
     }
     finalizeSynchronousJSExecution();