Fix issues in "merge existing and new import maps"

Closes #10833.

source

@@ -109912,6 +109912,9 @@ dictionary <dfn dictionary>PromiseRejectionEventInit</dfn> : <span>EventInit</sp
     <var>newImportMapImports</var> below.</p>
    </li>
 
+  <li><p>Let <var>oldImportMap</var> be <var>global</var>'s <span
+  data-x="concept-global-import-map">import map</span>.</p></li>
+
    <li><p>Let <var>newImportMapImports</var> be a deep copy of <var>newImportMap</var>'s <span
    data-x="concept-import-map-imports">imports</span>.</p></li>
     <!-- XXX "deep copy" ought to be defined. -->
@@ -109964,7 +109967,7 @@ dictionary <dfn dictionary>PromiseRejectionEventInit</dfn> : <span>EventInit</sp
              ignored rule. They may choose to avoid reporting if the rule is identical to an existing
              one.</p></li>
 
-             <li><p>Remove <var>scopeImports</var>[<var>specifier</var>].</p></li>
+             <li><p>Remove <var>scopeImports</var>[<var>specifierKey</var>].</p></li>
             </ol>
            </li>
           </ol>