Improve LayoutTest output for Errors

LayoutTests/crypto/aes-cbc-generateKey-parseAlgorithm-failures.html

Index: LayoutTests/crypto/aes-cbc-generateKey-parseAlgorithm-failures.html
diff --git a/LayoutTests/crypto/aes-cbc-generateKey-parseAlgorithm-failures.html b/LayoutTests/crypto/aes-cbc-generateKey-parseAlgorithm-failures.html
index ef0b91de105df66862982e4550f0765664494914..a7e60ab9b1a6cc2a84f06d3edc2a2c0b218af515 100644
--- a/LayoutTests/crypto/aes-cbc-generateKey-parseAlgorithm-failures.html
+++ b/LayoutTests/crypto/aes-cbc-generateKey-parseAlgorithm-failures.html
@@ -16,33 +16,37 @@ extractable = true;
 keyUsages = ['encrypt', 'decrypt'];
 
 Promise.resolve(null).then(function() {
-    // Invalid keyUsages
+    debug("\ngenerateKey() with invalid keyUsages value that is -1...");
     return crypto.subtle.generateKey({ name: 'aes-cbc', length: 1024 }, extractable, -1);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);
 
-    // Invalid keyUsages
+    debug("\ngenerateKey() with invalid keyUsages value that is null...");
     return crypto.subtle.generateKey({ name: 'aes-cbc', length: 1024 }, extractable, null);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);
 
-    // Bad key usage "boo".
+    debug("\ngenerateKey() with an invalid key usage of 'boo'...");
     return crypto.subtle.generateKey({ name: 'aes-cbc', length: 1024 }, extractable, ['boo']);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);
 
+    debug("\ngenerateKey() without length...");
     return crypto.subtle.generateKey({ name: 'aes-cbc' }, extractable, keyUsages);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);
 
+    debug("\ngenerateKey() with a length of 70000...");
     return crypto.subtle.generateKey({ name: 'aes-cbc', length: 70000 }, extractable, keyUsages);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);
 
+    debug("\ngenerateKey() with a length of -3...");
     return crypto.subtle.generateKey({ name: 'aes-cbc', length: -3 }, extractable, keyUsages);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);
 
+    debug("\ngenerateKey() with length that is minus Infinity...");
     return crypto.subtle.generateKey({ name: 'aes-cbc', length: -Infinity }, extractable, keyUsages);
 }).then(failAndFinishJSTest, function(result) {
     logError(result);