Introduce FieldIndex to unify and abstract property/field offset

test/cctest/test-heap.cc

Index: test/cctest/test-heap.cc
diff --git a/test/cctest/test-heap.cc b/test/cctest/test-heap.cc
index 158e146967ce067485272c37ca6df11976066004..b86b96db009cade488d690739f39329fc47eb20e 100644
--- a/test/cctest/test-heap.cc
+++ b/test/cctest/test-heap.cc
@@ -1018,7 +1018,9 @@ TEST(Regression39128) {
   CHECK_EQ(0, FixedArray::cast(jsobject->elements())->length());
   CHECK_EQ(0, jsobject->properties()->length());
   // Create a reference to object in new space in jsobject.
-  jsobject->FastPropertyAtPut(-1, array);
+  FieldIndex index = FieldIndex::ForInObjectOffset(
+      JSObject::kHeaderSize - kPointerSize);
+  jsobject->FastPropertyAtPut(index, array);
 
   CHECK_EQ(0, static_cast<int>(*limit_addr - *top_addr));
 
@@ -2318,13 +2320,17 @@ TEST(OptimizedPretenuringMixedInObjectProperties) {
       v8::Utils::OpenHandle(*v8::Handle<v8::Object>::Cast(res));
 
   CHECK(CcTest::heap()->InOldPointerSpace(*o));
-  CHECK(CcTest::heap()->InOldPointerSpace(o->RawFastPropertyAt(0)));
-  CHECK(CcTest::heap()->InOldDataSpace(o->RawFastPropertyAt(1)));
+  FieldIndex idx1 = FieldIndex::ForPropertyIndex(o->map(), 0);
+  FieldIndex idx2 = FieldIndex::ForPropertyIndex(o->map(), 1);
+  CHECK(CcTest::heap()->InOldPointerSpace(o->RawFastPropertyAt(idx1)));
+  CHECK(CcTest::heap()->InOldDataSpace(o->RawFastPropertyAt(idx2)));
 
-  JSObject* inner_object = reinterpret_cast<JSObject*>(o->RawFastPropertyAt(0));
+  JSObject* inner_object =
+      reinterpret_cast<JSObject*>(o->RawFastPropertyAt(idx1));
   CHECK(CcTest::heap()->InOldPointerSpace(inner_object));
-  CHECK(CcTest::heap()->InOldDataSpace(inner_object->RawFastPropertyAt(0)));
-  CHECK(CcTest::heap()->InOldPointerSpace(inner_object->RawFastPropertyAt(1)));
+  CHECK(CcTest::heap()->InOldDataSpace(inner_object->RawFastPropertyAt(idx1)));
+  CHECK(CcTest::heap()->InOldPointerSpace(
+      inner_object->RawFastPropertyAt(idx2)));
 }
 
 
@@ -3081,9 +3087,9 @@ TEST(Regress2211) {
     CHECK(value->Equals(obj->GetHiddenValue(v8_str("key string"))));
 
     // Check size.
-    DescriptorArray* descriptors = internal_obj->map()->instance_descriptors();
+    FieldIndex index = FieldIndex::ForDescriptor(internal_obj->map(), 0);
     ObjectHashTable* hashtable = ObjectHashTable::cast(
-        internal_obj->RawFastPropertyAt(descriptors->GetFieldIndex(0)));
+        internal_obj->RawFastPropertyAt(index));
     // HashTable header (5) and 4 initial entries (8).
     CHECK_LE(hashtable->SizeFor(hashtable->length()), 13 * kPointerSize);
   }