Keep a canonical list of shared function infos.

src/runtime/runtime-function.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/cpu-profiler.h"
@@ skipping 214 matching lines @@
   source_shared->set_dont_flush(true);
 
   // Set the code, scope info, formal parameter count, and the length
   // of the target shared function info.
   target_shared->ReplaceCode(source_shared->code());
   target_shared->set_scope_info(source_shared->scope_info());
   target_shared->set_length(source_shared->length());
   target_shared->set_feedback_vector(source_shared->feedback_vector());
   target_shared->set_internal_formal_parameter_count(
       source_shared->internal_formal_parameter_count());
-  target_shared->set_script(source_shared->script());
   target_shared->set_start_position_and_type(
       source_shared->start_position_and_type());
   target_shared->set_end_position(source_shared->end_position());
   bool was_native = target_shared->native();
   target_shared->set_compiler_hints(source_shared->compiler_hints());
   target_shared->set_opt_count_and_bailout_reason(
       source_shared->opt_count_and_bailout_reason());
   target_shared->set_native(was_native);
   target_shared->set_profiler_ticks(source_shared->profiler_ticks());
+  SharedFunctionInfo::SetScript(
+      target_shared, Handle<Object>(source_shared->script(), isolate));
 
   // Set the code of the target function.
   target->ReplaceCode(source_shared->code());
   DCHECK(target->next_function_link()->IsUndefined());
 
   // Make sure we get a fresh copy of the literal vector to avoid cross
   // context contamination.
   Handle<Context> context(source->context());
   int number_of_literals = source->NumberOfLiterals();
   Handle<FixedArray> literals =
@@ skipping 368 matching lines @@
 
 
 RUNTIME_FUNCTION(Runtime_ThrowStrongModeTooFewArguments) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 0);
   THROW_NEW_ERROR_RETURN_FAILURE(isolate,
                                  NewTypeError(MessageTemplate::kStrongArity));
 }
 }  // namespace internal
 }  // namespace v8