Add more invalid constructor call tests for X509Certificate2.

TestNullConstructorArguments was written, but missing [Fact].  InvalidCertificateBlob was added to help track down the SegFault in the X509 tests.

Author: bartonjs

src/System.Security.Cryptography.X509Certificates/tests/CtorTests.cs

@@ -71,6 +71,7 @@ public static void TestByteArrayConstructor()
             }
         }
 
+        [Fact]
         public static void TestNullConstructorArguments()
         {
             Assert.Throws<ArgumentException>(() => new X509Certificate2((byte[])null, (String)null));
@@ -98,5 +99,11 @@ public static void TestNullConstructorArguments()
                 }
             }
         }
+
+        [Fact]
+        public static void InvalidCertificateBlob()
+        {
+            Assert.Throws<CryptographicException>(() => new X509Certificate2(new byte[] { 0x01, 0x02, 0x03 }));
+        }
     }
 }