https://bugs.webkit.org/show_bug.cgi?id=108209

Reviewed by Dimitri Glazkov.

Source/WebCore:

Many of the exception cases for ShadowRoot are actually impossible and
should be asserts instead. We can also move the one case of exception logic,
for elements that don't allow author shadows into Element::createShadowRoot
instead of having it all over the ShadowRoot and ElementShadow classes. This
is the first step in centralizing all ShadowRoot creation inside ElementShadow.

No new tests, covered by existing tests.

* WebCore.exp.in:
* dom/Element.cpp:
(WebCore::Element::createShadowRoot): Be explicit about what kind of ShadowRoot you're creating.
(WebCore::Element::ensureUserAgentShadowRoot): No more exceptions.
* dom/ElementShadow.cpp:
(WebCore::ElementShadow::addShadowRoot): This never actually throws exceptions, remove ExceptionCode.
* dom/ElementShadow.h:
(ElementShadow):
* dom/ShadowRoot.cpp:
(WebCore::determineUsageType): Merge with Element::createShadowRoot.
(WebCore):
(WebCore::ShadowRoot::ShadowRoot): Moved Histogram logic here since it's actually about the constructor anyway.
(WebCore::ShadowRoot::create): Removed overload that made the code less obvious.
* dom/ShadowRoot.h:
(ShadowRoot):
* html/HTMLKeygenElement.cpp:
(WebCore::HTMLKeygenElement::HTMLKeygenElement):
* html/shadow/TextFieldDecorationElement.cpp:
(WebCore::getDecorationRootAndDecoratedRoot):
* testing/Internals.cpp:
(WebCore::Internals::ensureShadowRoot):
(WebCore::Internals::createShadowRoot):

Source/WebKit/win:

* WebKit.vcproj/WebKitExports.def.in: Swap ShadowRoot::create export with Element::createShadowRoot.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141175 268f45cc-cd09-0410-ab3c-d52691b4dbfc