Revert "VM: Materialize stub pc-markers (smi 0) eagerly on deoptimization."

runtime/vm/deopt_instructions.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/deopt_instructions.h"
 
 #include "vm/assembler.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/intermediate_language.h"
@@ skipping 633 matching lines @@
 
   virtual intptr_t source_index() const { return object_table_index_; }
   virtual DeoptInstr::Kind kind() const { return kPcMarker; }
 
   virtual const char* ArgumentsToCString() const {
     return Thread::Current()->zone()->PrintToString(
         "%" Pd "", object_table_index_);
   }
 
   void Execute(DeoptContext* deopt_context, intptr_t* dest_addr) {
-    Function& function = Function::Handle(deopt_context->zone());
-    function ^= deopt_context->ObjectAt(object_table_index_);
-    if (function.IsNull()) {
-      // Callee's PC marker is not used (pc of Deoptimize stub). Set to 0.
-      *dest_addr = Smi::RawValue(0);
-      return;
-    }
+    *dest_addr = Smi::RawValue(0);
     deopt_context->DeferPcMarkerMaterialization(
         object_table_index_, dest_addr);
   }
 
  private:
   intptr_t object_table_index_;
 
   DISALLOW_COPY_AND_ASSIGN(DeoptPcMarkerInstr);
 };
 
@@ skipping 629 matching lines @@
                           Smi* offset,
                           TypedData* info,
                           Smi* reason) {
   intptr_t i = index * kEntrySize;
   *offset ^= table.At(i);
   *info ^= table.At(i + 1);
   *reason ^= table.At(i + 2);
 }
 
 }  // namespace dart