Morph the APIs for Node, ParentNode, and Element closer to the specs

sky/engine/core/dom/Element.h

Index: sky/engine/core/dom/Element.h
diff --git a/sky/engine/core/dom/Element.h b/sky/engine/core/dom/Element.h
index 4b046b80b0047a8769b49a6b83c17b593d533a58..fbfe3298813c430319c29d7012eaab7957d0288e 100644
--- a/sky/engine/core/dom/Element.h
+++ b/sky/engine/core/dom/Element.h
@@ -76,6 +76,9 @@ public:
     bool hasAttribute(const AtomicString& name) const;
     const AtomicString& getAttribute(const AtomicString& name) const;
     void setAttribute(const AtomicString& name, const AtomicString& value, ExceptionState&);
+    void setAttribute(const AtomicString& name, ExceptionState& es) {

[esprehn, 2015/02/13 23:53:48]

default this to null in the idl instead?

[abarth-chromium, 2015/02/13 23:59:45]

I don't think this function is ever called but the code generator is dumb and
tries to link against this symbol.  I'm happy to fix the code generator in a
future CL.

+        setAttribute(name, String(), es);
+    }
     void removeAttribute(const AtomicString& name);
     void removeAttribute(const QualifiedName&);