Remove the CSSOM.

sky/engine/core/css/StylePropertySet.cpp

Index: sky/engine/core/css/StylePropertySet.cpp
diff --git a/sky/engine/core/css/StylePropertySet.cpp b/sky/engine/core/css/StylePropertySet.cpp
index e13059b9bbacae1a12a9ff188bb257008c3280fd..66803bb2a920f65e9adfe7ee1731d5df6d9e5178 100644
--- a/sky/engine/core/css/StylePropertySet.cpp
+++ b/sky/engine/core/css/StylePropertySet.cpp
@@ -498,7 +498,6 @@ CSSStyleDeclaration* MutableStylePropertySet::ensureCSSStyleDeclaration()
     // FIXME: get rid of this weirdness of a CSSStyleDeclaration inside of a
     // style property set.
     if (m_cssomWrapper) {
-        ASSERT(!static_cast<CSSStyleDeclaration*>(m_cssomWrapper.get())->parentRule());
         ASSERT(!m_cssomWrapper->parentElement());
         return m_cssomWrapper.get();
     }