Add null check to animations for registered custom property initial values

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

Index: third_party/WebKit/Source/core/animation/CSSInterpolationType.cpp
diff --git a/third_party/WebKit/Source/core/animation/CSSInterpolationType.cpp b/third_party/WebKit/Source/core/animation/CSSInterpolationType.cpp
index c15db7de439ddc884aa8f714245b961ac1073afd..26f23618931360efb4859b6a3b267bcfe1613e57 100644
--- a/third_party/WebKit/Source/core/animation/CSSInterpolationType.cpp
+++ b/third_party/WebKit/Source/core/animation/CSSInterpolationType.cpp
@@ -87,6 +87,12 @@ class InheritedCustomPropertyChecker
     if (!inheritedValue) {
       inheritedValue = m_initialValue.get();
     }
+    if (inheritedValue == m_inheritedValue.get()) {
+      return true;
+    }
+    if (!inheritedValue || !m_inheritedValue) {
+      return false;
+    }
     return m_inheritedValue->equals(*inheritedValue);
   }
 
@@ -207,20 +213,23 @@ CSSInterpolationType::maybeConvertCustomPropertyDeclarationInternal(
       return nullptr;
     }
 
+    const CSSValue* value = nullptr;
     if (declaration.isInitial(isInheritedProperty)) {
-      return maybeConvertValue(*registration->initial(), state,
-                               conversionCheckers);
+      value = registration->initial();
+    } else {
+      value =
+          state.parentStyle()->getRegisteredVariable(name, isInheritedProperty);
+      if (!value) {
+        value = registration->initial();
+      }
+      conversionCheckers.push_back(InheritedCustomPropertyChecker::create(
+          name, isInheritedProperty, value, registration->initial()));
     }
-
-    DCHECK(declaration.isInherit(isInheritedProperty));
-    const CSSValue* inheritedValue =
-        state.parentStyle()->getRegisteredVariable(name, isInheritedProperty);
-    if (!inheritedValue) {
-      inheritedValue = registration->initial();
+    if (!value) {
+      return nullptr;
     }
-    conversionCheckers.push_back(InheritedCustomPropertyChecker::create(
-        name, isInheritedProperty, inheritedValue, registration->initial()));
-    return maybeConvertValue(*inheritedValue, state, conversionCheckers);
+
+    return maybeConvertValue(*value, state, conversionCheckers);
   }
 
   if (declaration.value()->needsVariableResolution()) {
@@ -263,6 +272,9 @@ InterpolationValue CSSInterpolationType::maybeConvertUnderlyingValue(
   if (!underlyingValue) {
     underlyingValue = registration->initial();
   }
+  if (!underlyingValue) {
+    return nullptr;
+  }
   // TODO(alancutter): Remove the need for passing in conversion checkers.
   ConversionCheckers dummyConversionCheckers;
   return maybeConvertValue(*underlyingValue, environment.state(),