Update equals (#85896)

Author: hrrrrustic

src/libraries/System.ComponentModel.TypeConverter/ref/System.ComponentModel.TypeConverter.cs

@@ -1164,7 +1164,7 @@ public PropertyTabAttribute(System.Type tabClass, System.ComponentModel.Property
         public System.Type[] TabClasses { get { throw null; } }
         protected string[]? TabClassNames { get { throw null; } }
         public System.ComponentModel.PropertyTabScope[] TabScopes { get { throw null; } }
-        public bool Equals(System.ComponentModel.PropertyTabAttribute other) { throw null; }
+        public bool Equals([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] System.ComponentModel.PropertyTabAttribute? other) { throw null; }
         public override bool Equals([System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] object? other) { throw null; }
         public override int GetHashCode() { throw null; }
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("The Types referenced by tabClassNames may be trimmed.")]

src/libraries/System.ComponentModel.TypeConverter/src/System/ComponentModel/Design/PropertyTabAttribute.cs

@@ -145,34 +145,25 @@ private void InitializeTabClasses()
         public PropertyTabScope[] TabScopes { get; private set; }
 
         public override bool Equals([NotNullWhen(true)] object? other)
-        {
-            if (other is PropertyTabAttribute propertyTabAttribute)
-            {
-                return Equals(propertyTabAttribute);
-            }
-            return false;
-        }
+            => Equals(other as PropertyTabAttribute);
 
-        public bool Equals(PropertyTabAttribute other)
+        public bool Equals([NotNullWhen(true)] PropertyTabAttribute? other)
         {
-            if (other == (object)this)
-            {
+            if (other is null)
+                return false;
+
+            if (ReferenceEquals(this, other))
                 return true;
-            }
-            if (other.TabClasses.Length != TabClasses.Length ||
-                other.TabScopes.Length != TabScopes.Length)
-            {
+
+            if (other.TabClasses.Length != TabClasses.Length || other.TabScopes.Length != TabScopes.Length)
                 return false;
-            }
 
             for (int i = 0; i < TabClasses.Length; i++)
             {
-                if (TabClasses[i] != other.TabClasses[i] ||
-                    TabScopes[i] != other.TabScopes[i])
-                {
+                if (TabClasses[i] != other.TabClasses[i] || TabScopes[i] != other.TabScopes[i])
                     return false;
-                }
             }
+
             return true;
         }