Put live register bits in stackmaps.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index d8850f0164783e479e61bc791755321f3947bb6a..b9f2d4fc98eee754c0d49d8acb21a0225f3a3c9d 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -6792,7 +6792,9 @@ void Stackmap::SetBit(intptr_t bit_index, bool value) const {
 }
 
 
-RawStackmap* Stackmap::New(intptr_t pc_offset, BitmapBuilder* bmap) {
+RawStackmap* Stackmap::New(intptr_t pc_offset,
+                           BitmapBuilder* bmap,
+                           intptr_t register_count) {
   ASSERT(Object::stackmap_class() != Class::null());
   ASSERT(bmap != NULL);
   Stackmap& result = Stackmap::Handle();
@@ -6825,6 +6827,7 @@ RawStackmap* Stackmap::New(intptr_t pc_offset, BitmapBuilder* bmap) {
   for (intptr_t i = 0; i < length; ++i) {
     result.SetBit(i, bmap->Get(i));
   }
+  result.SetRegisterCount(register_count);
   return result.raw();
 }