Implement "create an element" when sync for Custom Element V1

third_party/WebKit/Source/core/dom/custom/CustomElement.h

Index: third_party/WebKit/Source/core/dom/custom/CustomElement.h
diff --git a/third_party/WebKit/Source/core/dom/custom/CustomElement.h b/third_party/WebKit/Source/core/dom/custom/CustomElement.h
index b4637109016095e548aa896aefdf71e9aaad1d7d..3c2dcaf0dc10e7e143cc719d65e81d841a85afea 100644
--- a/third_party/WebKit/Source/core/dom/custom/CustomElement.h
+++ b/third_party/WebKit/Source/core/dom/custom/CustomElement.h
@@ -55,11 +55,14 @@ public:
     static bool shouldCreateCustomElement(Document&, const QualifiedName&);
 
     static HTMLElement* createCustomElement(Document&, const AtomicString& localName, CreateElementFlags);
+    static HTMLElement* createCustomElement(Document&, const AtomicString& localName, CreateElementFlags, ExceptionState&);
     static HTMLElement* createCustomElement(Document&, const QualifiedName&, CreateElementFlags);
+    static HTMLElement* createCustomElement(Document&, const QualifiedName&, CreateElementFlags, ExceptionState&);
 
     static void enqueueUpgradeReaction(Element*, CustomElementDefinition*);
 
 private:
+    static HTMLElement* createCustomElement(Document&, const QualifiedName&, CreateElementFlags, ExceptionState*);

[dominicc (has gone to gerrit), 2016/06/10 06:13:28]

I don't like how things have ended up here. You have ExceptionState/no
ExceptionState variants because the caller needs us to swallow (and report)
exceptions or transmit them back.

Then you compress that down to this method with an optional exception state.

Then you decompress that to overloads which do/don't take ExceptionState.

Why not give these methods which behave really differently different names and
the right signatures, and have them each call the exactly right implementation?
So:

createCustomElementSync(..., ExceptionState&);
createCustomElementSync(...);
createCustomElementAsync(...);

This is better. It stops the caller from doing something weird like "create
custom element asynchronously and put exception state here." There's nothing
that needs that AFAIK, and we don't implement that, but your signatures support
that. Seems complex and error prone. Let's keep it simple.

I DON'T think we need the create element flags here (what are they used for
except sync/async?)

[kojii, 2016/06/10 19:01:45]

Done. It used to use CreatedByParser too, but that was replaced by optional
ExceptionState.

     static HTMLElement* createCustomElementAsync(Document&, CustomElementDefinition&, const QualifiedName&);
 };