Oilpan: reinstate nullptr initialization following r199382.

Source/core/inspector/InspectorCSSAgent.cpp

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 1505 matching lines @@
             return nullptr;
     }
 
     Document* ownerDocument = element->ownerDocument();
     // A non-active document has no styles.
     if (!ownerDocument->isActive())
         return nullptr;
 
     String longhand = getPropertyNameString(propertyId);
 
-    RefPtrWillBeRawPtr<CSSStyleDeclaration> foundStyle;
+    RefPtrWillBeRawPtr<CSSStyleDeclaration> foundStyle = nullptr;
     bool isImportant = false;
 
     if (inlineStyle && !inlineStyle->getPropertyValue(longhand).isEmpty()) {
         foundStyle = inlineStyle;
         isImportant = inlineStyle->getPropertyPriority(longhand) == "important";
     }
 
     StyleResolver& styleResolver = ownerDocument->ensureStyleResolver();
     element->updateDistribution();
     RefPtrWillBeRawPtr<CSSRuleList> ruleList = styleResolver.pseudoCSSRulesForElement(element, elementPseudoId, StyleResolver::AllCSSRules);
@@ skipping 135 matching lines @@
     visitor->trace(m_documentToCSSStyleSheets);
     visitor->trace(m_invalidatedDocuments);
     visitor->trace(m_nodeToInspectorStyleSheet);
     visitor->trace(m_documentToViaInspectorStyleSheet);
 #endif
     visitor->trace(m_inspectorUserAgentStyleSheet);
     InspectorBaseAgent::trace(visitor);
 }
 
 } // namespace blink