Merge pull request #108 from WebAssembly/instance-lookup

Instance lookup function for Wasm Namespaces

Author: guybedford

document/js-api/index.bs

@@ -80,6 +80,7 @@ urlPrefix: https://tc39.github.io/ecma262/; spec: ECMASCRIPT
         text: Cyclic Module Record; url: cyclic-module-record
         text: GetMethod; url: sec-getmethod
         text: ToBigInt64; url: #sec-tobigint64
+        text: Module Namespace exotic object; url: #sec-module-namespace-exotic-objects
     type: abstract-op
         text: CreateDataPropertyOrThrow; url: sec-createdatapropertyorthrow
         text: CreateMethodProperty; url: sec-createmethodproperty
@@ -631,6 +632,7 @@ Note: Some implementations enforce a size limitation on |bytes|. Use of this API
 interface Instance {
   constructor(Module module, optional object importObject);
   readonly attribute object exports;
+  static Instance namespaceInstance(ModuleNamespace moduleNamespace);
 };
 </pre>
 
@@ -648,6 +650,14 @@ Note: The use of this synchronous API is discouraged, as some implementations so
     The getter of the <dfn attribute for="Instance">exports</dfn> attribute of {{Instance}} returns **this**.\[[Exports]].
 </div>
 
+<div algorithm>
+    The <dfn method for="Instance">namespaceInstance(|namespace|)</dfn> method, when invoked, performs the following steps:
+    1. Assert: |namespace| is a [=Module Namespace exotic object=].
+    1. If |namespace|.\[[Module]] is not a [=WebAssembly Module Record=], [=throw=] a {{TypeError}} exception.
+    1. Let |module| be |namespace|.\[[Module]].
+    1. Return |module|.\[[Instance]].
+</div>
+
 <h3 id="memories">Memories</h3>
 
 <pre class="idl">