Editorial: a few spelling fixes

Author: dbaron

index.bs

@@ -1260,7 +1260,7 @@ must additionally include the [=interface mixin member|members=] of [=interface
 [=interface mixin=] |M|.
 
 <pre highlight="webidl" class="syntax">
-    interface_identifier includes mixin_indentifier;
+    interface_identifier includes mixin_identifier;
 </pre>
 
 The first [=identifier=] must reference a [=interface=] |I|.
@@ -6805,11 +6805,11 @@ type is the concatenation of the type name for |T| and the string
 
 <h4 id="idl-observable-array" interface lt="ObservableArrayT|ObservableArray&lt;T&gt;">Observable array types — ObservableArray&lt;|T|&gt;</h4>
 
-An <dfn id="dfn-observable-array-type" export>observable array type</dfn> is a parametrized type
+An <dfn id="dfn-observable-array-type" export>observable array type</dfn> is a parameterized type
 whose values are references to a combination of a mutable list of objects of type |T|, as well as
 behavior to perform when author code modifies the contents of the list.
 
-The parametrized type must not be a [=dictionary type=], [=sequence type=], or [=record type=].
+The parameterized type must not be a [=dictionary type=], [=sequence type=], or [=record type=].
 
 Similar to [=sequence types=] and [=frozen array types=], observable array types wrap around
 ECMAScript array types, imposing additional semantics on their usage.