Explicitly set CryptoKey.type to "secret" in AES and HMAC operations (#378)

Set `CryptoKey.type` to "secret" in the generate key and import key
operations of AES and HMAC.

These are strongly suggested to be "secret" anyway, per the description
of https://w3c.github.io/webcrypto/#dom-keytype.

However, it seems best to set them explicitly, as is done in the other
algorithms.

Author: BenWiederhake

spec/Overview.html

@@ -10226,6 +10226,12 @@ <h4>Operations</h4>
                     |normalizedAlgorithm|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Set the {{CryptoKey/[[algorithm]]}} internal
@@ -10379,6 +10385,12 @@ <h4>Operations</h4>
                     value |data|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Let |algorithm| be a new
@@ -10760,6 +10772,12 @@ <h4>Operations</h4>
                     |normalizedAlgorithm|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Set the {{CryptoKey/[[algorithm]]}} internal
@@ -10914,6 +10932,12 @@ <h4>Operations</h4>
                     object representing an AES key with value |data|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Let |algorithm| be a new
@@ -11378,6 +11402,12 @@ <h4>Operations</h4>
                     |normalizedAlgorithm|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Set the {{CryptoKey/[[algorithm]]}} internal
@@ -11532,6 +11562,12 @@ <h4>Operations</h4>
                     object representing an AES key with value |data|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Let |algorithm| be a new
@@ -11854,6 +11890,12 @@ <h4>Operations</h4>
                     |normalizedAlgorithm|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Set the {{CryptoKey/[[algorithm]]}} internal
@@ -12008,6 +12050,12 @@ <h4>Operations</h4>
                     representing an AES key with value |data|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Let |algorithm| be a new
@@ -12392,6 +12440,12 @@ <h4>Operations</h4>
                     of |algorithm| to |hash|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Set the {{CryptoKey/[[algorithm]]}} internal
@@ -12646,6 +12700,12 @@ <h4>Operations</h4>
                     bits of |data|.
                   </p>
                 </li>
+                <li>
+                  <p>
+                    Set the {{CryptoKey/[[type]]}} internal slot of
+                    |key| to {{KeyType/"secret"}}.
+                  </p>
+                </li>
                 <li>
                   <p>
                     Let |algorithm| be a new