Remove unused irregexp cache.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/200303002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@19934 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/interpreter-irregexp.cc

@@ -159,24 +159,11 @@ static int32_t Load16Aligned(const byte* pc) {
 class BacktrackStack {
  public:
   explicit BacktrackStack(Isolate* isolate) : isolate_(isolate) {
-    if (isolate->irregexp_interpreter_backtrack_stack_cache() != NULL) {
-      // If the cache is not empty reuse the previously allocated stack.
-      data_ = isolate->irregexp_interpreter_backtrack_stack_cache();
-      isolate->set_irregexp_interpreter_backtrack_stack_cache(NULL);
-    } else {
-      // Cache was empty. Allocate a new backtrack stack.
-      data_ = NewArray<int>(kBacktrackStackSize);
-    }
+    data_ = NewArray<int>(kBacktrackStackSize);
   }
 
   ~BacktrackStack() {
-    if (isolate_->irregexp_interpreter_backtrack_stack_cache() == NULL) {
-      // The cache is empty. Keep this backtrack stack around.
-      isolate_->set_irregexp_interpreter_backtrack_stack_cache(data_);
-    } else {
-      // A backtrack stack was already cached, just release this one.
-      DeleteArray(data_);
-    }
+    DeleteArray(data_);
   }
 
   int* data() const { return data_; }

src/isolate.h

@@ -353,8 +353,6 @@ typedef List<HeapObject*> DebugObjectCache;
   V(Relocatable*, relocatable_top, NULL)                                       \
   V(DebugObjectCache*, string_stream_debug_object_cache, NULL)                 \
   V(Object*, string_stream_current_security_token, NULL)                       \
-  /* TODO(isolates): Release this on destruction? */                           \
-  V(int*, irregexp_interpreter_backtrack_stack_cache, NULL)                    \
   /* Serializer state. */                                                      \
   V(ExternalReferenceTable*, external_reference_table, NULL)                   \
   /* AstNode state. */                                                         \