Remove useless null checks from Node::document() call sites

Source/core/svg/SVGElementRareData.h

Index: Source/core/svg/SVGElementRareData.h
diff --git a/Source/core/svg/SVGElementRareData.h b/Source/core/svg/SVGElementRareData.h
index 262000a359204700da97de50f6a9480d25413eea..fe3dcbad1f6174ffe60aba259bf177900b3f5dd8 100644
--- a/Source/core/svg/SVGElementRareData.h
+++ b/Source/core/svg/SVGElementRareData.h
@@ -90,7 +90,7 @@ public:
     RenderStyle* overrideComputedStyle(Element* element, RenderStyle* parentStyle)
     {
         ASSERT(element);
-        if (!element->document() || !m_useOverrideComputedStyle)
+        if (!m_useOverrideComputedStyle)
             return 0;
         if (!m_overrideComputedStyle || m_needsOverrideComputedStyleUpdate) {
             // The style computed here contains no CSS Animations/Transitions or SMIL induced rules - this is needed to compute the "base value" for the SMIL animation sandwhich model.