Enable preemption in d8.

src/execution.h

Index: src/execution.h
===================================================================
--- src/execution.h	(revision 1141)
+++ src/execution.h	(working copy)
@@ -228,7 +228,12 @@
 class StackLimitCheck BASE_EMBEDDED {
  public:
   bool HasOverflowed() const {
-    return reinterpret_cast<uintptr_t>(this) < StackGuard::climit();
+    // Stack has overflowed in C++ code only if stack pointer exceeds the C++
+    // stack guard and the limits are not set to interrupt values.
+    // TODO(214): Stack overflows are ignored if a interrupt is pending. This
+    // code should probably always use the initial C++ limit.
+    return (reinterpret_cast<uintptr_t>(this) < StackGuard::climit()) &&
+           StackGuard::IsStackOverflow();
   }
 };