Use new downcast helper for blink::SVGAnimateMotionElement

This CL has two goals,
  1. Use DynamicTo<SVGAnimateMotionElement> as new downcast helper
  2. Use IsA<SVGAnimateMotionElement>(element) in place of
     IsSVGAnimateMotionElement(element)

Bug: 891908
Change-Id: Idd892a19c8b958253fd0fa7296f1cc803f8cf9a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1936569Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Abhijeet | Igalia <abhijeet@igalia.com>
Cr-Commit-Position: refs/heads/master@{#720403}

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

@@ -187,7 +187,7 @@ void SVGAnimationElement::ParseAttribute(
   }
 
   if (name == svg_names::kKeyPointsAttr) {
-    if (IsSVGAnimateMotionElement(*this)) {
+    if (IsA<SVGAnimateMotionElement>(*this)) {
       // This is specified to be an animateMotion attribute only but it is
       // simpler to put it here where the other timing calculatations are.
       if (!ParseKeyTimes(params.new_value, key_points_, false)) {
@@ -316,12 +316,12 @@ void SVGAnimationElement::SetCalcMode(const AtomicString& calc_mode) {
     UseCounter::Count(GetDocument(), WebFeature::kSVGCalcModeDiscrete);
     SetCalcMode(kCalcModeDiscrete);
   } else if (calc_mode == linear) {
-    if (IsSVGAnimateMotionElement(*this))
+    if (IsA<SVGAnimateMotionElement>(*this))
       UseCounter::Count(GetDocument(), WebFeature::kSVGCalcModeLinear);
     // else linear is the default.
     SetCalcMode(kCalcModeLinear);
   } else if (calc_mode == paced) {
-    if (!IsSVGAnimateMotionElement(*this))
+    if (!IsA<SVGAnimateMotionElement>(*this))
       UseCounter::Count(GetDocument(), WebFeature::kSVGCalcModePaced);
     // else paced is the default.
     SetCalcMode(kCalcModePaced);
@@ -329,8 +329,8 @@ void SVGAnimationElement::SetCalcMode(const AtomicString& calc_mode) {
     UseCounter::Count(GetDocument(), WebFeature::kSVGCalcModeSpline);
     SetCalcMode(kCalcModeSpline);
   } else {
-    SetCalcMode(IsSVGAnimateMotionElement(*this) ? kCalcModePaced
-                                                 : kCalcModeLinear);
+    SetCalcMode(IsA<SVGAnimateMotionElement>(*this) ? kCalcModePaced
+                                                    : kCalcModeLinear);
   }
 }
 

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

@@ -92,7 +92,7 @@ void SVGMPathElement::TargetPathChanged() {
 }
 
 void SVGMPathElement::NotifyParentOfPathChange(ContainerNode* parent) {
-  if (auto* motion = ToSVGAnimateMotionElementOrNull(parent))
+  if (auto* motion = DynamicTo<SVGAnimateMotionElement>(parent))
     motion->UpdateAnimationPath();
 }