Add LayoutTests for WebCrypto's ECDH algorithm.

LayoutTests/crypto/ecdh-generate-key.html

Index: LayoutTests/crypto/ecdh-generate-key.html
diff --git a/LayoutTests/crypto/ecdsa-generate-key.html b/LayoutTests/crypto/ecdh-generate-key.html
similarity index 71%
copy from LayoutTests/crypto/ecdsa-generate-key.html
copy to LayoutTests/crypto/ecdh-generate-key.html
index 8bf2ff3db5d9514c705ee97553be32a4b8d04069..82de0a7f41d8bd470a2ba078942952c5744ab971 100644
--- a/LayoutTests/crypto/ecdsa-generate-key.html
+++ b/LayoutTests/crypto/ecdh-generate-key.html
@@ -9,28 +9,28 @@
 <div id="console"></div>
 
 <script>
-description("Test generating an EC key pair for ECDSA.");
+description("Test generating an EC key pair for ECDH.");
 
 jsTestIsAsync = true;
 
 var algorithmKeyGen = {
-    name: "ecdsa",
+    name: "ecdh",
     namedCurve: "P-256",
 };
 var extractable = true;
 
 debug("Generating a key pair...");
-crypto.subtle.generateKey(algorithmKeyGen, extractable, ["sign", "verify"]).then(function(result) {
+crypto.subtle.generateKey(algorithmKeyGen, extractable, ["deriveBits"]).then(function(result) {
     keyPair = result;
     shouldBe("keyPair.toString()", "'[object Object]'");
     shouldBe("keyPair.publicKey.type", "'public'");
-    shouldBe("keyPair.publicKey.algorithm.name", "'ECDSA'");
+    shouldBe("keyPair.publicKey.algorithm.name", "'ECDH'");
     shouldBe("keyPair.publicKey.algorithm.namedCurve", "'P-256'");
-    shouldBe("keyPair.publicKey.usages", '["verify"]');
+    shouldBe("keyPair.publicKey.usages", '[]');
     shouldBe("keyPair.privateKey.type", "'private'");
-    shouldBe("keyPair.privateKey.algorithm.name", "'ECDSA'");
+    shouldBe("keyPair.privateKey.algorithm.name", "'ECDH'");
     shouldBe("keyPair.privateKey.algorithm.namedCurve", "'P-256'");
-    shouldBe("keyPair.privateKey.usages", '["sign"]');
+    shouldBe("keyPair.privateKey.usages", '["deriveBits"]');
 
     debug("\nTesting that custom attributes on keys survive garbage collection...");
     keyPair.publicKey.foo = "bar";