Add fromCSSValue methods to LengthValue subclasses, remove extra method in CSSSimpleLength.

third_party/WebKit/Source/core/css/cssom/CSSCalcLength.cpp

Index: third_party/WebKit/Source/core/css/cssom/CSSCalcLength.cpp
diff --git a/third_party/WebKit/Source/core/css/cssom/CSSCalcLength.cpp b/third_party/WebKit/Source/core/css/cssom/CSSCalcLength.cpp
index 878ed5be782d8eafcc60a19b7860cd0610b84958..b2455c63847872d053ecfa7a4bde5f78fa420f6e 100644
--- a/third_party/WebKit/Source/core/css/cssom/CSSCalcLength.cpp
+++ b/third_party/WebKit/Source/core/css/cssom/CSSCalcLength.cpp
@@ -4,6 +4,7 @@
 
 #include "core/css/cssom/CSSCalcLength.h"
 
+#include "bindings/core/v8/ExceptionState.h"
 #include "core/css/CSSCalculationValue.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/css/cssom/CSSCalcDictionary.h"
@@ -68,6 +69,12 @@ CSSCalcLength* CSSCalcLength::create(const CSSCalcDictionary& dictionary, Except
     return result;
 }
 
+CSSCalcLength* CSSCalcLength::fromCSSValue(const CSSPrimitiveValue&)
+{
+    // TODO(meade): Implement.
+    return nullptr;
+}
+
 bool CSSCalcLength::containsPercent() const
 {
     return has(CSSPrimitiveValue::UnitType::Percentage);