Delta encode pc descriptors.

runtime/vm/raw_object.cc

Index: runtime/vm/raw_object.cc
diff --git a/runtime/vm/raw_object.cc b/runtime/vm/raw_object.cc
index 2d83e8f80994802238d5262a4c6b2b05fb52f16a..c45af8fe3e2612d512a0490e317ba039849c9261 100644
--- a/runtime/vm/raw_object.cc
+++ b/runtime/vm/raw_object.cc
@@ -142,11 +142,8 @@ intptr_t RawObject::SizeFromClass() const {
     case kPcDescriptorsCid: {
       const RawPcDescriptors* raw_descriptors =
           reinterpret_cast<const RawPcDescriptors*>(this);
-      const intptr_t num_descriptors = raw_descriptors->ptr()->length_;
-      const intptr_t rec_size_in_bytes =
-          raw_descriptors->ptr()->record_size_in_bytes_;
-      instance_size = PcDescriptors::InstanceSize(num_descriptors,
-                                                  rec_size_in_bytes);
+      intptr_t length = raw_descriptors->ptr()->length_;
+      instance_size = PcDescriptors::InstanceSize(length);
       break;
     }
     case kStackmapCid: {
@@ -563,8 +560,7 @@ intptr_t RawPcDescriptors::RecordSize(bool has_try_index) {
 
 intptr_t RawPcDescriptors::VisitPcDescriptorsPointers(
     RawPcDescriptors* raw_obj, ObjectPointerVisitor* visitor) {
-  return PcDescriptors::InstanceSize(raw_obj->ptr()->length_,
-                                     raw_obj->ptr()->record_size_in_bytes_);
+  return PcDescriptors::InstanceSize(raw_obj->ptr()->length_);
 }