Use new downcast helper for blink::SVGTextContentElement

Bug: 891908
Change-Id: I6fdac09b795461c2f1de6be177b2ce141fcab529
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1715006
Commit-Queue: Abhijeet Kandalkar <abhijeet@igalia.com>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680459}

third_party/blink/renderer/core/dom/tree_scope.cc

@@ -284,7 +284,7 @@ static bool ShouldAcceptNonElementNode(const Node& node) {
   // SVG text content elements has no background, and are thus not
   // hit during the background phase of hit-testing. Because of that
   // we need to allow any child (Text) node of these elements.
-  return IsSVGTextContentElement(*parent);
+  return IsA<SVGTextContentElement>(parent);
 }
 
 HeapVector<Member<Element>> TreeScope::ElementsFromHitTestResult(

third_party/blink/renderer/core/paint/text_paint_timing_detector_test.cc

@@ -621,8 +621,7 @@ TEST_F(TextPaintTimingDetectorTest, CaptureSVGText) {
     </svg>
   )HTML");
 
-  SVGTextContentElement* elem =
-      ToSVGTextContentElement(GetDocument().QuerySelector("text"));
+  auto* elem = To<SVGTextContentElement>(GetDocument().QuerySelector("text"));
   UpdateAllLifecyclePhasesAndSimulateSwapTime();
 
   EXPECT_EQ(CountVisibleTexts(), 1u);

third_party/blink/renderer/core/svg/svg_text_content_element.cc

@@ -60,8 +60,7 @@ class SVGAnimatedTextLength final : public SVGAnimatedLength {
                           SVGLength::Initial::kUnitlessZero) {}
 
   SVGLengthTearOff* baseVal() override {
-    SVGTextContentElement* text_content_element =
-        ToSVGTextContentElement(ContextElement());
+    auto* text_content_element = To<SVGTextContentElement>(ContextElement());
     if (!text_content_element->TextLengthIsSpecifiedByUser())
       BaseValue()->NewValueSpecifiedUnits(
           CSSPrimitiveValue::UnitType::kNumber,
@@ -280,10 +279,8 @@ SVGTextContentElement* SVGTextContentElement::ElementFromLineLayoutItem(
       (!line_layout_item.IsSVGText() && !line_layout_item.IsSVGInline()))
     return nullptr;
 
-  auto* element = To<SVGElement>(line_layout_item.GetNode());
-  DCHECK(element);
-  return IsSVGTextContentElement(*element) ? ToSVGTextContentElement(element)
-                                           : nullptr;
+  DCHECK(line_layout_item.GetNode());
+  return DynamicTo<SVGTextContentElement>(line_layout_item.GetNode());
 }
 
 }  // namespace blink

third_party/blink/renderer/core/svg/svg_text_content_element.h

@@ -96,7 +96,13 @@ inline bool IsSVGTextContentElement(const SVGElement& element) {
   return element.IsTextContent();
 }
 
-DEFINE_SVGELEMENT_TYPE_CASTS_WITH_FUNCTION(SVGTextContentElement);
+template <>
+struct DowncastTraits<SVGTextContentElement> {
+  static bool AllowFrom(const Node& node) {
+    auto* svg_element = DynamicTo<SVGElement>(node);
+    return svg_element && IsSVGTextContentElement(*svg_element);
+  }
+};
 
 }  // namespace blink
 

third_party/blink/renderer/core/svg/svg_text_content_element_test.cc

@@ -13,8 +13,7 @@ class SVGTextContentElementTest : public EditingTestBase {};
 
 TEST_F(SVGTextContentElementTest, selectSubStringNotCrash) {
   SetBodyContent("<svg><text style='visibility:hidden;'>Text</text></svg>");
-  SVGTextContentElement* elem =
-      ToSVGTextContentElement(GetDocument().QuerySelector("text"));
+  auto* elem = To<SVGTextContentElement>(GetDocument().QuerySelector("text"));
   VisiblePosition start = VisiblePosition::FirstPositionInNode(
       *const_cast<SVGTextContentElement*>(elem));
   EXPECT_TRUE(start.IsNull());