Localized code cleanup

Jint/Runtime/ExpressionIntepreter.cs

@@ -194,10 +194,13 @@ namespace Jint.Runtime
 
         public JsValue EvaluateBinaryExpression(BinaryExpression expression)
         {
-            JsValue left = _engine.GetValue(EvaluateExpression(expression.Left));
-            JsValue right = _engine.GetValue(EvaluateExpression(expression.Right));
-            JsValue value;
+            var leftExpression = EvaluateExpression(expression.Left);
+            JsValue left = _engine.GetValue(leftExpression);
+
+            var rightExpression = EvaluateExpression(expression.Right);
+            JsValue right = _engine.GetValue(rightExpression);
 
+            JsValue value;
               
             switch (expression.Operator)
             {

Jint/Runtime/References/Reference.cs

@@ -48,7 +48,7 @@ namespace Jint.Runtime.References
         public bool IsPropertyReference()
         {
             // http://www.ecma-international.org/ecma-262/5.1/#sec-8.7
-            return (_baseValue.IsObject() && _baseValue.TryCast<EnvironmentRecord>() == null) || HasPrimitiveBase();
+            return (_baseValue.IsObject() && !_baseValue.Is<EnvironmentRecord>()) || HasPrimitiveBase();
         }
     }
 }