Adds support for PKCS12 containers to SecurityContext

tests/standalone/io/security_context_argument_test.dart

Index: tests/standalone/io/security_context_argument_test.dart
diff --git a/tests/standalone/io/security_context_argument_test.dart b/tests/standalone/io/security_context_argument_test.dart
index 60577b245751a89ed33953db6afaf957cdd86a22..391708a933c652ec72718e5eb262f868fa63bed4 100644
--- a/tests/standalone/io/security_context_argument_test.dart
+++ b/tests/standalone/io/security_context_argument_test.dart
@@ -34,6 +34,25 @@ void testUsePrivateKeyArguments() {
     Expect.throws(() => c.usePrivateKeySync(
         localFile('certificates/server_key.pem'), password: 3),
         argumentOrTypeError);
+
+    // Malformed PEM certs.
+    Expect.throws(() => c.usePrivateKeySync(
+        localFile('certificates/client1_key_malformed.pem'),
+        password: "dartdart"),
+        tlsException);
+    Expect.throws(() => c.setTrustedCertificatesSync(
+        localFile('certificates/trusted_certs_malformed.pem')),
+        tlsException);
+    Expect.throws(() => c.useCertificateChainSync(
+        localFile('certificates/server_chain_malformed1.pem')),
+        tlsException);
+    Expect.throws(() => c.useCertificateChainSync(
+        localFile('certificates/server_chain_malformed2.pem')),
+        tlsException);
+    Expect.throws(() => c.setClientAuthoritiesSync(
+        localFile('certificates/client_authority_malformed.pem')),
+        argumentError);
+
     c.usePrivateKeySync(
         localFile('certificates/server_key.pem'), password: "dartdart");
 }