Do not stop evaluation of scripts moved between element documents for now

The previous CL [1] was intended to add use counter only, but
actually accidentally stopped execution of scripts moved between
different element documents under a same context document.

This CL partially reverts [1], and
makes such scripts evaluated again as before.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1843509

Bug: 721914
Change-Id: I13f5dbdff46c14a5da49e436994cf73a7dd88373
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1851524
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704549}

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

@@ -153,8 +153,6 @@ void PendingScript::ExecuteScriptBlock(const KURL& document_url) {
     // such scripts. https://crbug.com/721914
     UseCounter::Count(context_document,
                       WebFeature::kEvaluateScriptMovedBetweenElementDocuments);
-    Dispose();
-    return;
   }
 
   Script* script = GetSource(document_url);