Implement Custom Elements inserted and removed callbacks.

Implement Custom Elements inserted and removed callbacks.

This also fixes the order in which the ready callback is dispatched as
a result of parsing.

BUG=247166

[dominicc (has gone to gerrit), 2013-06-25 17:03:19]

This depends on Issue 17639010 going first.

[dglazkov, 2013-06-25 18:04:31]

LGTM.

The tests are great! Did you write them with W3C conformance test suite in mind?

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
File Source/core/dom/CustomElementCallback.h (right):

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
Source/core/dom/CustomElementCallback.h:40: class CustomElementCallback : public
RefCounted<CustomElementCallback> {
I wonder if these should be named CustomElementLifecycleCallbacks or something
to match the spec. I like how you put them all into one class.

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
File Source/core/dom/CustomElementCallbackDispatcher.h (right):

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
Source/core/dom/CustomElementCallbackDispatcher.h:50: class
CallbackDeliveryScope {
Do you still use this guy?

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
File Source/core/dom/CustomElementRegistry.cpp (right):

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
Source/core/dom/CustomElementRegistry.cpp:215: void
CustomElementRegistry::didGiveTypeExtension(Element* element, const
AtomicString& type, bool byParser)
givenByParser? or just createdByParser for consistency?

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
File Source/core/dom/CustomElementRegistry.h (right):

https://codereview.chromium.org/17707002/diff/1/Source/core/dom/CustomElement...
Source/core/dom/CustomElementRegistry.h:64: PassRefPtr<Element>
createCustomTagElement(const QualifiedName& localName, bool createdByParser);
Can we use enum here and elsewhere instead of a bool? Enums are more
descriptive.

[abarth-chromium, 2013-06-25 21:13:56]

https://codereview.chromium.org/17707002/diff/1/Source/bindings/v8/CustomElem...
File Source/bindings/v8/CustomElementConstructorBuilder.cpp (right):

https://codereview.chromium.org/17707002/diff/1/Source/bindings/v8/CustomElem...
Source/bindings/v8/CustomElementConstructorBuilder.cpp:156:
v8::Handle<v8::Value> value = m_prototype->Get(v8String(name, isolate));
Would you be willing to add a test that hooks each of these calls in JavaScript
with __defineGetter__ and blows away the document?  I want to make sure to see
ClusterFuzz with those tests cases.  (Maybe you've already done that.)