add SourcesEqual concrete method

spec.emu

@@ -1059,6 +1059,15 @@ contributors: Luca Casonato, Guy Bedford
                 <p>For Module Records that do not have a source representation, GetModuleSource() must always return a throw completion whose [[Value]] is a *ReferenceError*.</p>
               </td>
             </tr>
+            <tr>
+              <td>
+                <ins>SourcesEqual(_otherModuleRecord_)</ins>
+              </td>
+              <td>
+                <p><ins>For Module Records that implement a normal completion for GetModuleSource(), allows defining a source equality operation for host registry checks.</ins></p>
+                <p><ins>For Module Records that do not have a source representation, SourcesEqual() is never called.</ins></p>
+              </td>
+            </tr>
             <tr>
               <td>
                 <ins>GetModuleSourceName()</ins>
@@ -1266,6 +1275,28 @@ contributors: Luca Casonato, Guy Bedford
           </emu-alg>
         </emu-clause>
 
+        <emu-clause id="sec-source-text-module-record-sourceequals" type="concrete method">
+          <h1>
+            <ins>
+              SourcesEqual (
+                _moduleA_: a Module Record
+              ): a Boolean
+            </ins>
+          </h1>
+          <dl class="header">
+            <dt>for</dt>
+            <dd>a Source Text Module Record _module_</dd>
+
+            <dt>description</dt>
+            <dd>Checks module source equality (not module instance equality) of this module record against another module record</dd>
+          </dl>
+          <emu-alg>
+            1. <ins>If _otherModule_ is not a Source Text Module Record, return *false*.</ins>
+            1. <ins>If _otherModule_.[[SourceText]] is equal to _module_.[[SourceText]], return *true*.</ins>
+            1. <ins>Return *false*.</ins>
+          </emu-alg>
+        </emu-clause>
+
         <emu-clause id="sec-source-text-module-record-getmodulesourcename" type="concrete method">
           <h1>
             <ins>