Editorial: Present never-invoked concrete methods more consistently.

objectER.CreateImmutableBinding:
Add an emu-alg that asserts it's never invoked.

moduleER.DeleteBinding:
Don't say it "refuses to delete bindings",
because that sounds like it throws an error if invoked,
when in fact it's never invoked.

spec.html

@@ -6507,6 +6507,9 @@ <h1>CreateMutableBinding ( _N_, _D_ )</h1>
         <emu-clause id="sec-object-environment-records-createimmutablebinding-n-s">
           <h1>CreateImmutableBinding ( _N_, _S_ )</h1>
           <p>The concrete Environment Record method CreateImmutableBinding is never used within this specification in association with object Environment Records.</p>
+          <emu-alg>
+            1. Assert: This method is never invoked.
+          </emu-alg>
         </emu-clause>
 
         <emu-clause id="sec-object-environment-records-initializebinding-n-v">
@@ -7192,7 +7195,7 @@ <h1>GetBindingValue ( _N_, _S_ )</h1>
 
         <emu-clause id="sec-module-environment-records-deletebinding-n">
           <h1>DeleteBinding ( _N_ )</h1>
-          <p>The concrete Environment Record method DeleteBinding for module Environment Records refuses to delete bindings.</p>
+          <p>The concrete Environment Record method DeleteBinding for module Environment Records is never invoked.</p>
           <emu-alg>
             1. Assert: This method is never invoked. See <emu-xref href="#sec-delete-operator-static-semantics-early-errors"></emu-xref>.
           </emu-alg>