Precompilation: don't include an object header for instructions in the text section.

runtime/vm/raw_object.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 1061 matching lines @@
     kInlinedCallerIdMapIndex = 2,
     kInlinedIdToTokenPosIndex = 3,
     kInlinedMetadataSize = 4,
   };
 
   RAW_HEAP_OBJECT_IMPLEMENTATION(Code);
 
   uword entry_point_;
 
   RawObject** from() {
-    return reinterpret_cast<RawObject**>(&ptr()->active_instructions_);
+    return reinterpret_cast<RawObject**>(&ptr()->instructions_);
   }
-  RawInstructions* active_instructions_;
-  RawInstructions* instructions_;
+  union {
+    RawInstructions* instructions_;
+    RawSmi* precompiled_instructions_size_;
+  };
   RawObjectPool* object_pool_;
   // If owner_ is Function::null() the owner is a regular stub.
   // If owner_ is a Class the owner is the allocation stub for that class.
   // Else, owner_ is a regular Dart Function.
   RawObject* owner_;  // Function, Null, or a Class.
   RawExceptionHandlers* exception_handlers_;
   RawPcDescriptors* pc_descriptors_;
   RawCodeSourceMap* code_source_map_;
   RawArray* stackmaps_;
   RawObject** to_snapshot() {
@@ skipping 1264 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_