Support animating <resolution> custom properties

third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp

Index: third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp b/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
index 5ea602d13bb1fb9c1219e3531e50691821669cba..cebcea45874f55be87fb65ec6cb60b78fc235771 100644
--- a/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
+++ b/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
@@ -265,6 +265,12 @@ double CSSPrimitiveValue::ComputeDegrees() const {
   }
 }
 
+double CSSPrimitiveValue::ComputeDotsPerPixel() const {
+  UnitType current_type = TypeWithCalcResolved();
+  DCHECK(IsResolution(current_type));
+  return GetDoubleValue() * ConversionToCanonicalUnitsScaleFactor(current_type);
+}
+
 template <>
 int CSSPrimitiveValue::ComputeLength(
     const CSSToLengthConversionData& conversion_data) const {