Optimize the common obfuscator pattern where ["foo","bar","baz"]

src/heap.h

Index: src/heap.h
===================================================================
--- src/heap.h	(revision 9139)
+++ src/heap.h	(working copy)
@@ -77,6 +77,7 @@
   V(Object, instanceof_cache_map, InstanceofCacheMap)                          \
   V(Object, instanceof_cache_answer, InstanceofCacheAnswer)                    \
   V(FixedArray, single_character_string_cache, SingleCharacterStringCache)     \
+  V(FixedArray, string_split_cache, StringSplitCache)                          \
   V(Object, termination_exception, TerminationException)                       \
   V(FixedArray, empty_fixed_array, EmptyFixedArray)                            \
   V(ByteArray, empty_byte_array, EmptyByteArray)                               \
@@ -2176,6 +2177,27 @@
 };
 
 
+class StringSplitCache {
+ public:
+  static Object* Lookup(FixedArray* cache, String* string, String* pattern);
+  static void Enter(Heap* heap,
+                    FixedArray* cache,
+                    String* string,
+                    String* pattern,
+                    FixedArray* array);
+  static void Clear(FixedArray* cache);
+  static const int kStringSplitCacheSize = 0x100;
+
+ private:
+  static const int kArrayEntriesPerCacheEntry = 4;
+  static const int kStringOffset = 0;
+  static const int kPatternOffset = 1;
+  static const int kArrayOffset = 2;
+
+  static MaybeObject* WrapFixedArrayInJSArray(Object* fixed_array);
+};
+
+
 class TranscendentalCache {
  public:
   enum Type {ACOS, ASIN, ATAN, COS, EXP, LOG, SIN, TAN, kNumberOfCaches};