[runtime] Return undefined as CallSite::getFunction for scripts

Scripts aren't callable functions. Even though internally they were for a
while, they aren't anymore. We shouldn't return them to users as if they were.
We already remove strict-mode functions from CallSites, so we now do the same
for internal functions that are created for scripts.

Bug: v8:10508
Change-Id: I270c714524439fba9ad90dd29826bed4811ba2b4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2193716
Auto-Submit: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67709}

src/builtins/builtins-callsite.cc

@@ -76,7 +76,11 @@ BUILTIN(CallSitePrototypeGetFunction) {
                         GetFrameIndex(isolate, recv));
 
   StackFrameBase* frame = it.Frame();
-  if (frame->IsStrict()) return ReadOnlyRoots(isolate).undefined_value();
+  if (frame->IsStrict() ||
+      (frame->GetFunction()->IsJSFunction() &&
+       JSFunction::cast(*frame->GetFunction()).shared().is_toplevel())) {
+    return ReadOnlyRoots(isolate).undefined_value();
+  }
 
   isolate->CountUsage(v8::Isolate::kCallSiteAPIGetFunctionSloppyCall);
 

test/mjsunit/regress/regress-10508.js

+// Copyright 2020 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.
+
+Error.prepareStackTrace = (error, frames) => {
+  // JSON.stringify executes the replacer, triggering the relevant
+  // code in Invoke().
+  JSON.stringify({}, frames[0].getFunction());
+};
+let v0;
+try {
+  throw new Error();
+} catch (e) {
+  e.stack
+}