Remove unused irregexp cache.

src/interpreter-irregexp.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 141 matching lines @@
 }
 
 
 // A simple abstraction over the backtracking stack used by the interpreter.
 // This backtracking stack does not grow automatically, but it ensures that the
 // the memory held by the stack is released or remembered in a cache if the
 // matching terminates.
 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_; }
 
   int max_size() const { return kBacktrackStackSize; }
 
  private:
   static const int kBacktrackStackSize = 10000;
 
   int* data_;
@@ skipping 448 matching lines @@
     return RawMatch(isolate,
                     code_base,
                     subject_vector,
                     registers,
                     start_position,
                     previous_char);
   }
 }
 
 } }  // namespace v8::internal