[webcrypto] Reject failed operations with a DOMException rather than null.

LayoutTests/crypto/rsa-es-generateKey-parseAlgorithm-failures.html

Index: LayoutTests/crypto/rsa-es-generateKey-parseAlgorithm-failures.html
diff --git a/LayoutTests/crypto/rsa-es-generateKey-parseAlgorithm-failures.html b/LayoutTests/crypto/rsa-es-generateKey-parseAlgorithm-failures.html
index f69ac6544192c595922287895bba81aa021d92cb..fc74c78f823c7de963a3dfd71f628da29b414b3f 100644
--- a/LayoutTests/crypto/rsa-es-generateKey-parseAlgorithm-failures.html
+++ b/LayoutTests/crypto/rsa-es-generateKey-parseAlgorithm-failures.html
@@ -18,33 +18,27 @@ keyUsages = ['encrypt', 'decrypt'];
 Promise.resolve(null).then(function() {
     return crypto.subtle.generateKey({name: 'RSAES-PKCS1-v1_5', modulusLength: -30}, extractable , keyUsages);
 }).then(failAndFinishJSTest, function(result) {
-    error = result;
-    shouldBeNull("error");
+    logError(result);
 
     return crypto.subtle.generateKey({name: 'RSAES-PKCS1-v1_5', modulusLength: NaN}, extractable , keyUsages);
 }).then(failAndFinishJSTest, function(result) {
-    error = result;
-    shouldBeNull("error");
+    logError(result);
 
     return crypto.subtle.generateKey({name: 'RSAES-PKCS1-v1_5'}, extractable , keyUsages);
 }).then(failAndFinishJSTest, function(result) {
-    error = result;
-    shouldBeNull("error");
+    logError(result);
 
     return crypto.subtle.generateKey({name: 'RSAES-PKCS1-v1_5', modulusLength: 10}, extractable , keyUsages);
 }).then(failAndFinishJSTest, function(result) {
-    error = result;
-    shouldBeNull("error");
+    logError(result);
 
     return crypto.subtle.generateKey({name: 'RSAES-PKCS1-v1_5', modulusLength: 10, publicExponent: 10}, extractable , keyUsages);
 }).then(failAndFinishJSTest, function(result) {
-    error = result;
-    shouldBeNull("error");
+    logError(result);
 
     return crypto.subtle.generateKey({name: 'RSAES-PKCS1-v1_5', modulusLength: 10, publicExponent: null}, extractable , keyUsages);
 }).then(failAndFinishJSTest, function(result) {
-    error = result;
-    shouldBeNull("error");
+    logError(result);
 }).then(finishJSTest, failAndFinishJSTest);
 
 </script>