Fix performance regression introduced by r12812.

src/regexp-stack.cc

Index: src/regexp-stack.cc
diff --git a/src/regexp-stack.cc b/src/regexp-stack.cc
index fda7253edcee150a6cac9668e0f9db726bd135ce..325a1496c98c9a26d05c9fffc1c97be132e401f0 100644
--- a/src/regexp-stack.cc
+++ b/src/regexp-stack.cc
@@ -51,6 +51,7 @@ RegExpStack::RegExpStack()
 
 
 RegExpStack::~RegExpStack() {
+  thread_local_.Free();
 }
 
 
@@ -72,7 +73,7 @@ char* RegExpStack::RestoreStack(char* from) {
 
 
 void RegExpStack::Reset() {
-  if (thread_local_.memory_size_ >= kMinimumStackSize) {
+  if (thread_local_.memory_size_ > kMinimumStackSize) {
     DeleteArray(thread_local_.memory_);
     thread_local_ = ThreadLocal();
   }