[runtime] Make %FunctionGetScript and %FunctionGetSourceCode robust.

src/runtime/runtime-function.cc

Index: src/runtime/runtime-function.cc
diff --git a/src/runtime/runtime-function.cc b/src/runtime/runtime-function.cc
index 938293b387c7f846c0e1655a48fd91c83fc8b0d5..e29b3c8c5f02f437934e42556e3dfa83029570ae 100644
--- a/src/runtime/runtime-function.cc
+++ b/src/runtime/runtime-function.cc
@@ -55,11 +55,14 @@ RUNTIME_FUNCTION(Runtime_FunctionGetScript) {
   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();
 }
 
 
@@ -67,8 +70,10 @@ 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();
 }