change wasm: error back to instantiation time

Author: Guy Bedford

document/js-api/index.bs

@@ -1387,9 +1387,8 @@ To <dfn export>parse a WebAssembly module</dfn> given a <a>byte sequence</a> |by
 1. [=Construct a WebAssembly module object=] from |module| and |bytes|, and let |module| be the result.
 1. Let |requestedModules| be a set.
 1. For each (|moduleName|, <var ignore>name</var>, <var ignore>type</var>) in [=module_imports=](|module|.\[[Module]]),
-    1. If |moduleName| starts with the string "wasm:",
-        1. Throw a {{CompileError}} exception.
-    1. [=set/Append=] |moduleName| to |requestedModules|.
+    1. If |moduleName| does not start with the builtin string prefix "wasm:",
+        1. [=set/Append=] |moduleName| to |requestedModules|.
 1. Return {
       <!-- Abstract Module Records -->
       \[[Realm]]: |realm|,
@@ -1412,7 +1411,7 @@ To <dfn export>parse a WebAssembly module</dfn> given a <a>byte sequence</a> |by
       \[[PendingAsyncDependencies]]: ~empty~,
     }.
 
-Node: When integrating with the JS String Builtins proposal, "<code data-x="">builtins: ["js-string"]</code>" should be provided in the above WebAssembly compilation options, with the corresponding builtin names permitted.
+Node: When integrating with the JS String Builtins proposal, "<code data-x="">builtins: ["js-string"]</code>" should be provided in the WebAssembly compilation options, with the corresponding builtin names permitted.
 
 Note: From HTML, it's not observable when [=parse a WebAssembly module=] begins, so any work perfomed in compilation may be performed off-thread.
 </div>
@@ -1466,6 +1465,9 @@ WebAssembly Module Records have the following methods:
 1. Let |module| be |record|.\[[ModuleSource]].
 1. Let |imports| be a new, empty [=map=].
 1. For each (|importedModuleName|, |name|, <var ignore>type</var>) in [=module_imports=](|module|.\[[Module]]),
+    1. If |moduleName| starts with the string "wasm:",
+        Note: when integrating with the JS String Builtins proposal, string builtins should be excluded from erroring here.
+        1. Throw a {{LinkError}} exception.
     1. If |imports|[|importedModuleName|] does not exist, set |imports|[|importedModuleName|] to a new, empty [=map=].
     1. Let |importedModule| be [$GetImportedModule$](|record|, |importedModuleName|).
     1. Let |value| be ? |importedModule|.\[[Environment]].GetBindingValue(|name|, true).