Signal a blocked futex if the isolate is interrupted; don't busy-wait

src/execution.cc

Index: src/execution.cc
diff --git a/src/execution.cc b/src/execution.cc
index d2dd41a12c6598ca170d80da314267382780e86e..9a1ab3597b3db011a1fb7e95ea9b6bd8d13e846f 100644
--- a/src/execution.cc
+++ b/src/execution.cc
@@ -413,6 +413,9 @@ void StackGuard::RequestInterrupt(InterruptFlag flag) {
   // Not intercepted.  Set as active interrupt flag.
   thread_local_.interrupt_flags_ |= flag;
   set_interrupt_limits(access);
+
+  // If this isolate is waiting in a futex, notify it to wake up.
+  isolate_->futex_wait_list_node()->NotifyWake();
 }