refactor: moved style comparison into dedicated method

Author: egil

src/AngleSharp.Diffing/Strategies/AttributeStrategies/StyleAttributeComparer.cs

@@ -29,7 +29,7 @@ private static CompareResult CompareElementStyle(in AttributeComparison comparis
             var (ctrlElm, testElm) = comparison.GetAttributeElements();
             var ctrlStyle = ctrlElm.GetStyle();
             var testStyle = testElm.GetStyle();
-            return ctrlStyle.CssText.Equals(testStyle.CssText, StringComparison.Ordinal)
+            return CompareCssStyleDeclarations(ctrlStyle, testStyle)
                 ? CompareResult.Same
                 : CompareResult.Different;
         }
@@ -39,5 +39,13 @@ private static bool IsStyleAttributeComparison(in AttributeComparison comparison
             return comparison.Control.Attribute.Name.Equals(AttributeNames.Style, StringComparison.Ordinal) &&
                 comparison.Test.Attribute.Name.Equals(AttributeNames.Style, StringComparison.Ordinal);
         }
+
+        private static bool CompareCssStyleDeclarations(ICssStyleDeclaration control, ICssStyleDeclaration test)
+        {
+            if(control.Length != test.Length)
+                return false;
+
+            return control.CssText.Equals(test.CssText, StringComparison.Ordinal);
+        }
     }
 }