Do not attempt to instantiate modules that have previously failed

Instead, propagate their instantiation errors. Closes whatwg#2556.

Author: domenic

source

@@ -87118,16 +87118,30 @@ interface <dfn>NavigatorOnLine</dfn> {
     propagated to the caller of this algorithm in the last step.</p>
    </li>
 
-   <li><p>Let <var>record</var> be <var>result</var>'s <span
-   data-x="concept-module-script-module-record">module record</span>.</p>
+   <li><p>Let <var>instantiationStatus</var> be null.</p></li>
+
+   <li><p>If <var>result</var>'s <span data-x="concept-module-script-instantiation-state">instantiation
+   state</span> is "<code data-x="">errored</code>", then set <var>instantiationStatus</var> to
+   Completion { [[Type]]: throw, [[Value]]: <var>result</var>'s <span
+   data-x="concept-module-script-instantiation-error">instantiation error</span>, [[Target]]:
+   empty }.</p></li>
 
    <li>
-    <p>Let <var>instantiationStatus</var> be <var>record</var>.<span
-    data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span>().</p>
+    <p>Otherwise:</p>
+
+    <ol>
+     <li><p>Let <var>record</var> be <var>result</var>'s <span
+     data-x="concept-module-script-module-record">module record</span>.</p></li>
 
-    <p class="note">This step will recursively call <span
-    data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span> all of the
-    module's uninstantiated dependencies.</p>
+     <li>
+      <p>Set <var>instantiationStatus</var> to <var>record</var>.<span
+      data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span>().</p>
+
+      <p class="note">This step will recursively call <span
+      data-x="js-ModuleDeclarationInstantiation">ModuleDeclarationInstantiation</span> all of the
+      module's uninstantiated dependencies.</p>
+     </li>
+    </ol>
    </li>
 
    <li>
@@ -120225,6 +120239,7 @@ INSERT INTERFACES HERE
   Geoff Richards,
   Geoffrey Garen,
   Geoffrey Sneddon,
+  Georg Neis,
   George Lund,
   Gianmarco Armellin,
   Giovanni Campagna,