Oilpan: move the GradientStop value object off the heap.

Source/core/css/CSSGradientValue.cpp

Index: Source/core/css/CSSGradientValue.cpp
diff --git a/Source/core/css/CSSGradientValue.cpp b/Source/core/css/CSSGradientValue.cpp
index a6563c95b5a99670bc229541982653a6a465de67..1f86b09498bbbc041709eaa367bd74a8273ea197 100644
--- a/Source/core/css/CSSGradientValue.cpp
+++ b/Source/core/css/CSSGradientValue.cpp
@@ -101,9 +101,7 @@ void CSSGradientValue::sortStopsIfNeeded()
     }
 }
 
-class GradientStop {
-    ALLOW_ONLY_INLINE_ALLOCATION();
-public:
+struct GradientStop {
     Color color;
     float offset;
     bool specified;
@@ -114,7 +112,7 @@ public:
     { }
 };
 
-void replaceColorHintsWithColorStops(WillBeHeapVector<GradientStop>& stops, const WillBeHeapVector<CSSGradientColorStop, 2>& cssGradientStops)
+static void replaceColorHintsWithColorStops(Vector<GradientStop>& stops, const WillBeHeapVector<CSSGradientColorStop, 2>& cssGradientStops)
 {
     // This algorithm will replace each color interpolation hint with 9 regular
     // color stops. The color values for the new color stops will be calculated
@@ -229,7 +227,7 @@ void CSSGradientValue::addStops(Gradient* gradient, const CSSToLengthConversionD
 
     size_t numStops = m_stops.size();
 
-    WillBeHeapVector<GradientStop> stops(numStops);
+    Vector<GradientStop> stops(numStops);
 
     float gradientLength = 0;
     bool computedGradientLength = false;