Make SVGLengthMode an enum class

Source/core/svg/PatternAttributes.h

Index: Source/core/svg/PatternAttributes.h
diff --git a/Source/core/svg/PatternAttributes.h b/Source/core/svg/PatternAttributes.h
index 6bd46240923aa315d2bb1f2e7d6735cb2510f6e1..757ce96328be1d9fb8cee6bb069abef07402bdc9 100644
--- a/Source/core/svg/PatternAttributes.h
+++ b/Source/core/svg/PatternAttributes.h
@@ -33,10 +33,10 @@ class PatternAttributes final {
     DISALLOW_ALLOCATION();
 public:
     PatternAttributes()
-        : m_x(SVGLength::create(LengthModeWidth))
-        , m_y(SVGLength::create(LengthModeHeight))
-        , m_width(SVGLength::create(LengthModeWidth))
-        , m_height(SVGLength::create(LengthModeHeight))
+        : m_x(SVGLength::create(SVGLengthMode::Width))
+        , m_y(SVGLength::create(SVGLengthMode::Height))
+        , m_width(SVGLength::create(SVGLengthMode::Width))
+        , m_height(SVGLength::create(SVGLengthMode::Height))
         , m_viewBox()
         , m_preserveAspectRatio(SVGPreserveAspectRatio::create())
         , m_patternUnits(SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX)