Add methods to allow resuming execution after calling TerminateExecution().

src/execution.cc

Index: src/execution.cc
===================================================================
--- src/execution.cc	(revision 12718)
+++ src/execution.cc	(working copy)
@@ -420,6 +420,17 @@
 }
 
 
+void StackGuard::ResumeExecution() {
+  ASSERT(thread_local_.interrupt_flags_ & TERMINATE);
+  ExecutionAccess access(isolate_);
+  thread_local_.interrupt_flags_ &= ~static_cast<int>(TERMINATE);
+  if (!should_postpone_interrupts(access) && !has_pending_interrupts(access)) {
+    reset_limits(access);
+  }
+  isolate_->ResumeExecution();
+}
+
+
 void StackGuard::TerminateExecution() {
   ExecutionAccess access(isolate_);
   thread_local_.interrupt_flags_ |= TERMINATE;