RFC: Try to be much more careful with where we skip the write barrier by:...

src/objects-inl.h

Index: src/objects-inl.h
===================================================================
--- src/objects-inl.h	(revision 3737)
+++ src/objects-inl.h	(working copy)
@@ -1349,7 +1349,7 @@
 }
 
 
-WriteBarrierMode HeapObject::GetWriteBarrierMode() {
+WriteBarrierMode HeapObject::GetWriteBarrierMode(const AssertNoAllocation&) {
   if (Heap::InNewSpace(this)) return SKIP_WRITE_BARRIER;
   return UPDATE_WRITE_BARRIER;
 }
@@ -1548,9 +1548,7 @@
 }
 
 void NumberDictionary::set_requires_slow_elements() {
-  set(kMaxNumberKeyIndex,
-      Smi::FromInt(kRequiresSlowElementsMask),
-      SKIP_WRITE_BARRIER);
+  set(kMaxNumberKeyIndex, Smi::FromInt(kRequiresSlowElementsMask));
 }
 
 
@@ -2973,7 +2971,8 @@
                                       PropertyDetails details) {
   ASSERT(!key->IsString() || details.IsDeleted() || details.index() > 0);
   int index = HashTable<Shape, Key>::EntryToIndex(entry);
-  WriteBarrierMode mode = FixedArray::GetWriteBarrierMode();
+  AssertNoAllocation no_gc;
+  WriteBarrierMode mode = FixedArray::GetWriteBarrierMode(no_gc);
   FixedArray::set(index, key, mode);
   FixedArray::set(index+1, value, mode);
   FixedArray::fast_set(this, index+2, details.AsSmi());
@@ -3007,8 +3006,13 @@
 }
 
 
+void JSArray::set_length(Smi* length) {
+  set_length(static_cast<Object*>(length), SKIP_WRITE_BARRIER);
+}
+
+
 void JSArray::SetContent(FixedArray* storage) {
-  set_length(Smi::FromInt(storage->length()), SKIP_WRITE_BARRIER);
+  set_length(Smi::FromInt(storage->length()));
   set_elements(storage);
 }