Handlify GetSourceCode-related functions.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index e4f165ae44e5e64051c8ea176e5687b6869ef11b..7d72466c4731e30a51aa0e13c4303c96978d6835 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -7615,13 +7615,10 @@ bool SharedFunctionInfo::HasSourceCode() {
 }
 
 
-Object* SharedFunctionInfo::GetSourceCode() {
-  Isolate* isolate = GetIsolate();
-  if (!HasSourceCode()) return isolate->heap()->undefined_value();
-  HandleScope scope(isolate);
-  Object* source = Script::cast(script())->source();
-  return *SubString(Handle<String>(String::cast(source), isolate),
-                    start_position(), end_position());
+Handle<Object> SharedFunctionInfo::GetSourceCode() {
+  if (!HasSourceCode()) return GetIsolate()->factory()->undefined_value();
+  Handle<String> source(String::cast(Script::cast(script())->source()));
+  return SubString(source, start_position(), end_position());
 }