Use the Document rather than the Frame's execution context to install JS-based marquee elements

Source/core/html/HTMLMarqueeElement.cpp

Index: Source/core/html/HTMLMarqueeElement.cpp
diff --git a/Source/core/html/HTMLMarqueeElement.cpp b/Source/core/html/HTMLMarqueeElement.cpp
index b53c7f06994733e74876b4b0b2fbc69eababc747..c17fa69bf2205585b1e89b5c9ca30a54cabbc9da 100644
--- a/Source/core/html/HTMLMarqueeElement.cpp
+++ b/Source/core/html/HTMLMarqueeElement.cpp
@@ -34,7 +34,7 @@ namespace blink {
 inline HTMLMarqueeElement::HTMLMarqueeElement(Document& document)
     : HTMLElement(HTMLNames::marqueeTag, document)
 {
-    v8::Handle<v8::Value> classObject = PrivateScriptRunner::installClassIfNeeded(document.frame(), "HTMLMarqueeElement");
+    v8::Handle<v8::Value> classObject = PrivateScriptRunner::installClassIfNeeded(&document, "HTMLMarqueeElement");
     RELEASE_ASSERT(!classObject.IsEmpty());

[adamk, 2014/10/22 17:38:45]

This RELEASE_ASSERT still looks scary to me. There's code in
Document::contextDocument() that'll sometimes return NULL, which would result in
a crash here. Why are we sure that it's impossible for a contextDocument's
m_frame to be non-empty? Or are we just sure that we won't be running the
HTMLMarqueeElement constructor at that time?

[haraken, 2014/10/23 00:52:05]

I think we can just remove installClassIfNeeded() completely, because
installClassIfNeeded() is lazily called when any private script API is invoked.

In this particular case, installClassIfNeeded() will be called when we call
V8HTMLMarqueeElement::PrivateScript::createdCallbackMethod(). If we don't have
any frame at that point, createdCallbackMethod() will return immediately without
doing nothing. (This is better than crashing, but it's still a wrong behavior.
We need a frame to execute a private script.)

I'll remove installClassIfNeeded() in a follow-up CL.

     UseCounter::count(document, UseCounter::HTMLMarqueeElement);
 }