Implement set trap for proxies, and revamp class hierarchy in preparation

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index b82c76aa830bcb249f919419e99e46b2c6f7410e..329fde849f93a1f500973b5bde293d889203cb43 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1060,9 +1060,8 @@ void MarkCompactCollector::MarkUnmarkedObject(HeapObject* object) {
       map->ClearCodeCache(heap());
     }
     SetMark(map);
-    if (FLAG_collect_maps &&
-        map->instance_type() >= FIRST_JS_OBJECT_TYPE &&
-        map->instance_type() <= JS_FUNCTION_TYPE) {
+    ASSERT(LAST_TYPE == LAST_FUNCTION_CLASS_TYPE);
+    if (FLAG_collect_maps && map->instance_type() >= FIRST_JS_RECEIVER_TYPE) {
       MarkMapContents(map);
     } else {
       marking_stack_.Push(map);
@@ -1139,8 +1138,8 @@ void MarkCompactCollector::CreateBackPointers() {
        next_object != NULL; next_object = iterator.next()) {
     if (next_object->IsMap()) {  // Could also be ByteArray on free list.
       Map* map = Map::cast(next_object);
-      if (map->instance_type() >= FIRST_JS_OBJECT_TYPE &&
-          map->instance_type() <= JS_FUNCTION_TYPE) {
+      ASSERT(LAST_TYPE == LAST_FUNCTION_CLASS_TYPE);
+      if (map->instance_type() >= FIRST_JS_RECEIVER_TYPE) {
         map->CreateBackPointers();
       } else {
         ASSERT(map->instance_descriptors() == heap()->empty_descriptor_array());
@@ -1516,8 +1515,8 @@ void MarkCompactCollector::ClearNonLiveTransitions() {
 
     ASSERT(SafeIsMap(map));
     // Only JSObject and subtypes have map transitions and back pointers.
-    if (map->instance_type() < FIRST_JS_OBJECT_TYPE) continue;
-    if (map->instance_type() > JS_FUNCTION_TYPE) continue;
+    ASSERT(LAST_TYPE == LAST_FUNCTION_CLASS_TYPE);
+    if (map->instance_type() < FIRST_JS_RECEIVER_TYPE) continue;
 
     if (map->IsMarked() && map->attached_to_shared_function_info()) {
       // This map is used for inobject slack tracking and has been detached