fixup! [js-api] Add support for exceptions.

document/js-api/index.bs

@@ -1185,7 +1185,8 @@ interface Exception {
 An {{Exception}} value represents a type of exception.
 {{Exception}} values have an <dfn for=Exception>exception tag</dfn>.
 
-The <dfn for=Exception>payload types</dfn> of an {{Exception}} is the [=list=] of types of
+The <dfn for=Exception>payload types</dfn> of an {{Exception}} is the [=list=] of types associated
+with its [=Exception/exception tag=].
 
 
 <h4 id="runtime-exceptions">Runtime exceptions</h4>
@@ -1202,15 +1203,13 @@ A {{RuntimeException}} value represents an [=exnref=] value.
 {{RuntimeException}} values have an <dfn for=RuntimeException>internal exception</dfn>, which
 is an [=event address=].
 
-Issue: Should it be possible to construct {{RuntimeException}} objects from JavaScript? Only with
-the [=JavaScript exception tag=] or also with others? How?
 <div algorithm>
 
 The <dfn constructor for=RuntimeException
 lt="RuntimeException(exceptionType, payload)">new RuntimeException(|exceptionType|, |payload|)</dfn>
 constructor steps are:
 
-1. Let |types| be |exceptionType|'s [=Exception/exception tag=]'s [=list=] of types.
+1. Let |types| be |exceptionType|'s [=Exception/payload types=].
 1. If |types|'s [=list/size=] is not |payload|'s [=list/size=],
     1. Throw a {{TypeError}}.
 1. Let |wasmPayload| be « ».