Implement tracking and optimizations of packed arrays

src/contexts.h

Index: src/contexts.h
diff --git a/src/contexts.h b/src/contexts.h
index 647c15c153ac54768cca4ea4c4f4a421b06f5dc5..d154b82ca06e2d547219b101b512cb204b807a40 100644
--- a/src/contexts.h
+++ b/src/contexts.h
@@ -106,9 +106,7 @@ enum BindingFlags {
   V(OBJECT_FUNCTION_INDEX, JSFunction, object_function) \
   V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function) \
   V(ARRAY_FUNCTION_INDEX, JSFunction, array_function) \
-  V(SMI_JS_ARRAY_MAP_INDEX, Object, smi_js_array_map) \
-  V(DOUBLE_JS_ARRAY_MAP_INDEX, Object, double_js_array_map) \
-  V(OBJECT_JS_ARRAY_MAP_INDEX, Object, object_js_array_map) \
+  V(JS_ARRAY_MAPS_INDEX, Object, js_array_maps) \
   V(DATE_FUNCTION_INDEX, JSFunction, date_function) \
   V(JSON_OBJECT_INDEX, JSObject, json_object) \
   V(REGEXP_FUNCTION_INDEX, JSFunction, regexp_function) \
@@ -248,9 +246,7 @@ class Context: public FixedArray {
     OBJECT_FUNCTION_INDEX,
     INTERNAL_ARRAY_FUNCTION_INDEX,
     ARRAY_FUNCTION_INDEX,
-    SMI_JS_ARRAY_MAP_INDEX,
-    DOUBLE_JS_ARRAY_MAP_INDEX,
-    OBJECT_JS_ARRAY_MAP_INDEX,
+    JS_ARRAY_MAPS_INDEX,
     DATE_FUNCTION_INDEX,
     JSON_OBJECT_INDEX,
     REGEXP_FUNCTION_INDEX,
@@ -373,18 +369,6 @@ class Context: public FixedArray {
   Object* OptimizedFunctionsListHead();
   void ClearOptimizedFunctions();
 
-  static int GetContextMapIndexFromElementsKind(
-      ElementsKind elements_kind) {
-    if (elements_kind == FAST_DOUBLE_ELEMENTS) {
-      return Context::DOUBLE_JS_ARRAY_MAP_INDEX;
-    } else if (elements_kind == FAST_ELEMENTS) {
-      return Context::OBJECT_JS_ARRAY_MAP_INDEX;
-    } else {
-      ASSERT(elements_kind == FAST_SMI_ONLY_ELEMENTS);
-      return Context::SMI_JS_ARRAY_MAP_INDEX;
-    }
-  }
-
 #define GLOBAL_CONTEXT_FIELD_ACCESSORS(index, type, name) \
   void  set_##name(type* value) {                         \
     ASSERT(IsGlobalContext());                            \