Webcrypto: add layout tests for HKDF algorithm

LayoutTests/crypto/subtle/hkdf-deriveBits-failures-expected.txt

Index: LayoutTests/crypto/subtle/hkdf-deriveBits-failures-expected.txt
diff --git a/LayoutTests/crypto/subtle/hkdf-deriveBits-failures-expected.txt b/LayoutTests/crypto/subtle/hkdf-deriveBits-failures-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..c4115c696ceb62d3d6d99cc556f4b67441accaf3
--- /dev/null
+++ b/LayoutTests/crypto/subtle/hkdf-deriveBits-failures-expected.txt
@@ -0,0 +1,18 @@
+Test bad inputs to HKDF deriveBits()
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+
+deriveBits() with an unsupported hash...
+error is: NotSupportedError: HkdfParams: hash: HMAC: Unsupported operation: digest
+
+deriveBits() with a key that doesn't match the algorithm...

[eroman, 2015/01/07 01:18:43]

would be better to say here "with an ECDH key" or some such thing.

[nharper, 2015/01/09 22:41:46]

Done.

+error is: InvalidAccessError: key.algorithm does not match that of operation
+
+deriveBits() with requested length too long...
+error is: OperationError: The length provided for HKDF is too large.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+