Rename default -> initial style and use singletons.

Source/core/css/CSSCalculationValueTest.cpp

Index: Source/core/css/CSSCalculationValueTest.cpp
diff --git a/Source/core/css/CSSCalculationValueTest.cpp b/Source/core/css/CSSCalculationValueTest.cpp
index 55733c7c7ea217d99dee5aa57bc20f7e996da668..38627035f6d2df376770a26f155deaff89660cfb 100644
--- a/Source/core/css/CSSCalculationValueTest.cpp
+++ b/Source/core/css/CSSCalculationValueTest.cpp
@@ -89,7 +89,7 @@ bool lengthArraysEqual(CSSLengthArray& a, CSSLengthArray& b)
 
 TEST(CSSCalculationValue, AccumulatePixelsAndPercent)
 {
-    RefPtr<LayoutStyle> style = LayoutStyle::createDefaultStyle();
+    RefPtr<LayoutStyle> style = LayoutStyle::create();
     style->setEffectiveZoom(5);
     CSSToLengthConversionData conversionData(style.get(), style.get(), nullptr, style->effectiveZoom());