Use isSVG*Element() helpers more in SVG code (Part 3)

Source/core/rendering/svg/ReferenceFilterBuilder.cpp

Index: Source/core/rendering/svg/ReferenceFilterBuilder.cpp
diff --git a/Source/core/rendering/svg/ReferenceFilterBuilder.cpp b/Source/core/rendering/svg/ReferenceFilterBuilder.cpp
index 784d43978233b8b09da544ee642feb652251b9e9..f135c1a3aa49ae5728251445bf98a5f2809315f7 100644
--- a/Source/core/rendering/svg/ReferenceFilterBuilder.cpp
+++ b/Source/core/rendering/svg/ReferenceFilterBuilder.cpp
@@ -134,10 +134,10 @@ PassRefPtr<FilterEffect> ReferenceFilterBuilder::build(Filter* parentFilter, Ren
         return nullptr;
     }
 
-    if (!filter->isSVGElement() || !filter->hasTagName(SVGNames::filterTag))
+    if (!isSVGFilterElement(*filter))
         return nullptr;
 
-    SVGFilterElement* filterElement = toSVGFilterElement(toSVGElement(filter));
+    SVGFilterElement& filterElement = toSVGFilterElement(*filter);
 
     // FIXME: Figure out what to do with SourceAlpha. Right now, we're
     // using the alpha of the original input layer, which is obviously
@@ -147,9 +147,9 @@ PassRefPtr<FilterEffect> ReferenceFilterBuilder::build(Filter* parentFilter, Ren
     RefPtr<SVGFilterBuilder> builder = SVGFilterBuilder::create(previousEffect, SourceAlpha::create(parentFilter));
 
     ColorSpace filterColorSpace = ColorSpaceDeviceRGB;
-    bool useFilterColorSpace = getSVGElementColorSpace(filterElement, filterColorSpace);
+    bool useFilterColorSpace = getSVGElementColorSpace(&filterElement, filterColorSpace);
 
-    for (SVGElement* element = Traversal<SVGElement>::firstChild(*filterElement); element; element = Traversal<SVGElement>::nextSibling(*element)) {
+    for (SVGElement* element = Traversal<SVGElement>::firstChild(filterElement); element; element = Traversal<SVGElement>::nextSibling(*element)) {
         if (!element->isFilterEffect())
             continue;
 
@@ -160,7 +160,7 @@ PassRefPtr<FilterEffect> ReferenceFilterBuilder::build(Filter* parentFilter, Ren
             continue;
 
         effectElement->setStandardAttributes(effect.get());
-        effect->setEffectBoundaries(SVGLengthContext::resolveRectangle<SVGFilterPrimitiveStandardAttributes>(effectElement, filterElement->primitiveUnits()->currentValue()->enumValue(), parentFilter->sourceImageRect()));
+        effect->setEffectBoundaries(SVGLengthContext::resolveRectangle<SVGFilterPrimitiveStandardAttributes>(effectElement, filterElement.primitiveUnits()->currentValue()->enumValue(), parentFilter->sourceImageRect()));
         ColorSpace colorSpace = filterColorSpace;
         if (useFilterColorSpace || getSVGElementColorSpace(effectElement, colorSpace))
             effect->setOperatingColorSpace(colorSpace);