Oilpan: fix build after r175261.

Add required parens.

R=
BUG=378167
NOTRY=true

Review URL: https://codereview.chromium.org/311563006

git-svn-id: svn://svn.chromium.org/blink/trunk@175268 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -705,7 +705,7 @@ String StylePropertySerializer::borderPropertyValue(CommonValueMode valueMode) c
 static void appendBackgroundRepeatValue(StringBuilder& builder, const CSSValue& repeatXCSSValue, const CSSValue& repeatYCSSValue)
 {
     // FIXME: Ensure initial values do not appear in CSS_VALUE_LISTS.
-    DEFINE_STATIC_REF_WILL_BE_PERSISTENT(CSSPrimitiveValue, initialRepeatValue, CSSPrimitiveValue::create(CSSValueRepeat));
+    DEFINE_STATIC_REF_WILL_BE_PERSISTENT(CSSPrimitiveValue, initialRepeatValue, (CSSPrimitiveValue::create(CSSValueRepeat)));
     const CSSPrimitiveValue& repeatX = repeatXCSSValue.isInitialValue() ? *initialRepeatValue : toCSSPrimitiveValue(repeatXCSSValue);
     const CSSPrimitiveValue& repeatY = repeatYCSSValue.isInitialValue() ? *initialRepeatValue : toCSSPrimitiveValue(repeatYCSSValue);
     CSSValueID repeatXValueId = repeatX.getValueID();