Support animating <number> custom properties

third_party/WebKit/Source/core/animation/CSSNumberInterpolationType.cpp

Index: third_party/WebKit/Source/core/animation/CSSNumberInterpolationType.cpp
diff --git a/third_party/WebKit/Source/core/animation/CSSNumberInterpolationType.cpp b/third_party/WebKit/Source/core/animation/CSSNumberInterpolationType.cpp
index 03954520d96541405d0015c69f3cadd1a917f976..3f9dca284d88c4a7cb146d123f22935dab599da1 100644
--- a/third_party/WebKit/Source/core/animation/CSSNumberInterpolationType.cpp
+++ b/third_party/WebKit/Source/core/animation/CSSNumberInterpolationType.cpp
@@ -36,6 +36,14 @@ class InheritedNumberChecker : public InterpolationType::ConversionChecker {
   const double m_number;
 };
 
+const CSSValue* CSSNumberInterpolationType::createCSSValue(
+    const InterpolableValue& value,
+    const NonInterpolableValue*,
+    const StyleResolverState&) const {
+  return CSSPrimitiveValue::create(toInterpolableNumber(value).value(),
+                                   CSSPrimitiveValue::UnitType::Number);
+}
+
 InterpolationValue CSSNumberInterpolationType::createNumberValue(
     double number) const {
   return InterpolationValue(InterpolableNumber::create(number));