[runtime] Make %FunctionGetScript and %FunctionGetSourceCode robust.

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/runtime/runtime-utils.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/frames-inl.h"
@@ skipping 37 matching lines @@
 
   return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(Runtime_FunctionGetScript) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, function, 0);
 
-  if (function->IsJSBoundFunction()) return isolate->heap()->undefined_value();
-  Handle<Object> script(Handle<JSFunction>::cast(function)->shared()->script(),
-                        isolate);
-  if (!script->IsScript()) return isolate->heap()->undefined_value();
-  return *Script::GetWrapper(Handle<Script>::cast(script));
+  if (function->IsJSFunction()) {
+    Handle<Object> script(
+        Handle<JSFunction>::cast(function)->shared()->script(), isolate);
+    if (script->IsScript()) {
+      return *Script::GetWrapper(Handle<Script>::cast(script));
+    }
+  }
+  return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(Runtime_FunctionGetSourceCode) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, function, 0);
-  if (function->IsJSBoundFunction()) return isolate->heap()->undefined_value();
-  return *Handle<JSFunction>::cast(function)->shared()->GetSourceCode();
+  if (function->IsJSFunction()) {
+    return *Handle<JSFunction>::cast(function)->shared()->GetSourceCode();
+  }
+  return isolate->heap()->undefined_value();
 }
 
 
 RUNTIME_FUNCTION(Runtime_FunctionGetScriptSourcePosition) {
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
 
   CONVERT_ARG_CHECKED(JSFunction, fun, 0);
   int pos = fun->shared()->start_position();
   return Smi::FromInt(pos);
@@ skipping 269 matching lines @@
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSReceiver, function, 0);
   return function->IsJSBoundFunction()
              ? *JSBoundFunction::ToString(
                    Handle<JSBoundFunction>::cast(function))
              : *JSFunction::ToString(Handle<JSFunction>::cast(function));
 }
 
 }  // namespace internal
 }  // namespace v8