Fix: Send Vary header consistently

Close #858

Author: Malvoz

web.config

@@ -107,7 +107,7 @@
                     <action type="Rewrite" value="{C:3}" />
                 </rule>
                 <!-- add vary header -->
-                <rule name="AddVaryAcceptEncoding" preCondition="PreCompressedFile" enabled="true">
+                <rule name="AddVaryAcceptEncoding" enabled="true">
                     <match serverVariable="RESPONSE_Vary" pattern=".*" />
                     <action type="Rewrite" value="Accept-Encoding" />
                 </rule>
@@ -122,9 +122,6 @@
                     <action type="Rewrite" value="gzip" />
                 </rule>
                 <preConditions>
-                    <preCondition name="PreCompressedFile">
-                        <add input="{HTTP_URL}" pattern="\.((?:css|html|ico|js|map|svg|txt|xml|webmanifest)\.(gz|br))" />
-                    </preCondition>
                     <preCondition name="PreCompressedZopfli">
                         <add input="{HTTP_URL}" pattern="\.((?:css|html|ico|js|map|svg|txt|xml|webmanifest)\.gz)" />
                     </preCondition>