Add test case to test that empty supported payment method identifiers throw TypeError.

third_party/WebKit/LayoutTests/payments/payment-request-interface.html

Index: third_party/WebKit/LayoutTests/payments/payment-request-interface.html
diff --git a/third_party/WebKit/LayoutTests/payments/payment-request-interface.html b/third_party/WebKit/LayoutTests/payments/payment-request-interface.html
index 29e70b7c11e748af6af07cfe74bb5612a7e5d9b2..3a65ab1713b09a53f3cd6c962ea3e0136fe5b260 100644
--- a/third_party/WebKit/LayoutTests/payments/payment-request-interface.html
+++ b/third_party/WebKit/LayoutTests/payments/payment-request-interface.html
@@ -243,6 +243,9 @@ generate_tests(assert_throws, [
     ['Empty list of supported payment method identifiers should throw TypeError.', new TypeError(), function() {
         new PaymentRequest([], buildDetails())
     }],
+    ['Empty supported payment method identifiers should throw TypeError.', null, function() {
+        new PaymentRequest([{'supportedMethods': []}], buildDetails())
+    }],
     ['Empty details should throw', null, function() {
         new PaymentRequest([{'supportedMethods': ['foo']}], {})
     }],