Put a comment in the right place

The "element_document.ExecutingFrame()" check is identical to what the
HTML Standard calls "the node's node document has a browsing context,"
which belongs in step 11.

Also per kouhei@'s request, add a TODO for switching to ExecutingWindow
rather than ExecutingFrame.

Change-Id: I653d303861c0e02e65d7e5de466fecd90a4806d1
Reviewed-on: https://chromium-review.googlesource.com/1171988
Commit-Queue: Timothy Gu <timothygu@chromium.org>
Reviewed-by: Dominic Farolino <domfarolino@gmail.com>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582699}

third_party/blink/renderer/core/script/script_loader.cc

@@ -301,15 +301,24 @@ bool ScriptLoader::PrepareScript(const TextPosition& script_start_position,
   //
   // FIXME: If script is parser inserted, verify it's still in the original
   // document.
+
+  // <spec step="11">If scripting is disabled for the script element, then
+  // return. The script is not executed.</spec>
+  //
+  // <spec
+  // href="https://html.spec.whatwg.org/multipage/webappapis.html#concept-n-noscript">
+  // Scripting is disabled for a node if [the node's node document has no
+  // browsing context], or if scripting is disabled in that browsing context.
+  // </spec>
   Document& element_document = element_->GetDocument();
-  Document* context_document = element_document.ContextDocument();
+  // TODO(timothygu): Investigate if we could switch from ExecutingFrame() to
+  // ExecutingWindow().
   if (!element_document.ExecutingFrame())
     return false;
+
+  Document* context_document = element_document.ContextDocument();
   if (!context_document || !context_document->ExecutingFrame())
     return false;
-
-  // <spec step="11">If scripting is disabled for the script element, then
-  // return. The script is not executed.</spec>
   if (!context_document->CanExecuteScripts(kAboutToExecuteScript))
     return false;