Oilpan: fix use of uninitialized raw pointers on the stack.

Source/core/css/parser/CSSPropertyParser.cpp

Index: Source/core/css/parser/CSSPropertyParser.cpp
diff --git a/Source/core/css/parser/CSSPropertyParser.cpp b/Source/core/css/parser/CSSPropertyParser.cpp
index 8881e39f396e593db520bb6677076a1a2db13738..c924f7cff4b339163465c5dddbb457bb495cc953 100644
--- a/Source/core/css/parser/CSSPropertyParser.cpp
+++ b/Source/core/css/parser/CSSPropertyParser.cpp
@@ -3132,9 +3132,9 @@ PassRefPtrWillBeRawPtr<CSSValue> CSSPropertyParser::parseAnimationProperty()
 
 bool CSSPropertyParser::parseWebkitTransformOriginShorthand(bool important)
 {
-    RefPtrWillBeRawPtr<CSSValue> originX;
-    RefPtrWillBeRawPtr<CSSValue> originY;
-    RefPtrWillBeRawPtr<CSSValue> originZ;
+    RefPtrWillBeRawPtr<CSSValue> originX = nullptr;
+    RefPtrWillBeRawPtr<CSSValue> originY = nullptr;
+    RefPtrWillBeRawPtr<CSSValue> originZ = nullptr;
 
     parse2ValuesFillPosition(m_valueList.get(), originX, originY);