Bug 1587905 - Remove useless variable 'bytesAllocated' declaration & assignation r=sfink

Differential Revision: https://phabricator.services.mozilla.com/D48888

--HG--
extra : moz-landing-system : lando

js/xpconnect/src/XPCJSRuntime.cpp

@@ -2901,10 +2901,9 @@ static nsresult ReadSourceFromFilename(JSContext* cx, const char* filename,
     ptr += bytesRead;
   }
 
-  size_t bytesAllocated;
   if (utf8Source) {
     // |buf| is already UTF-8, so we can directly return it.
-    *len = bytesAllocated = rawLen;
+    *len = rawLen;
     *utf8Source = buf.release();
   } else {
     MOZ_ASSERT(twoByteSource != nullptr);
@@ -2920,8 +2919,6 @@ static nsresult ReadSourceFromFilename(JSContext* cx, const char* filename,
     if (!*twoByteSource) {
       return NS_ERROR_FAILURE;
     }
-
-    bytesAllocated = *len * sizeof(char16_t);
   }
 
   return NS_OK;