Handle Color Color constant pattern (#16525)

Fixes #16517 

src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs

@@ -984,7 +984,7 @@ private BoundExpression BindArgList(CSharpSyntaxNode node, DiagnosticBag diagnos
         /// </summary>
         private BoundExpression BindQualifiedName(QualifiedNameSyntax node, DiagnosticBag diagnostics)
         {
-            return BindMemberAccessWithBoundLeft(node, this.BindExpression(node.Left, diagnostics), node.Right, node.DotToken, invoked: false, indexed: false, diagnostics: diagnostics);
+            return BindMemberAccessWithBoundLeft(node, this.BindLeftOfPotentialColorColorMemberAccess(node.Left, diagnostics), node.Right, node.DotToken, invoked: false, indexed: false, diagnostics: diagnostics);
         }
 
         private BoundExpression BindParenthesizedExpression(ExpressionSyntax innerExpression, DiagnosticBag diagnostics)

src/Compilers/CSharp/Test/Semantic/Semantics/PatternMatchingTests.cs

@@ -4313,6 +4313,36 @@ public static void Main()
         System.Console.WriteLine(six is two * three);
     }
 }
+";
+            var compilation = CreateCompilationWithMscorlib45(source, options: TestOptions.DebugExe);
+            compilation.VerifyDiagnostics();
+            var comp = CompileAndVerify(compilation, expectedOutput: "True");
+        }
+
+        [Fact]
+        public void ColorColorConstantPattern()
+        {
+            var source =
+@"
+public class Program
+{
+    public static Color Color { get; }
+
+    public static void M(object o)
+    {
+        System.Console.WriteLine(o is Color.Constant);
+    }
+
+    public static void Main()
+    {
+        M(Color.Constant);
+    }
+}
+
+public class Color
+{
+    public const string Constant = ""abc"";
+}
 ";
             var compilation = CreateCompilationWithMscorlib45(source, options: TestOptions.DebugExe);
             compilation.VerifyDiagnostics();