Make footer GWT UI link configurable

Change-Id: I8527fe876d4ccdc9244ad93bb58fbb60d179758d
diff --git a/polygerrit-ui/app/elements/gr-app.js b/polygerrit-ui/app/elements/gr-app.js
index 53ffc60..3b66ae8 100644
--- a/polygerrit-ui/app/elements/gr-app.js
+++ b/polygerrit-ui/app/elements/gr-app.js
@@ -197,7 +197,8 @@
     },
 
     _computeShowGwtUiLink(config) {
-      return config.gerrit.web_uis && config.gerrit.web_uis.includes('GWT');
+      return !window.DEPRECATE_GWT_UI &&
+          config.gerrit.web_uis && config.gerrit.web_uis.includes('GWT');
     },
 
     _handlePageError(e) {
diff --git a/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy b/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy
index c51e9dc..3dd6360 100644
--- a/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy
+++ b/resources/com/google/gerrit/httpd/raw/PolyGerritIndexHtml.soy
@@ -21,6 +21,7 @@
  * @param staticResourcePath
  * @param? faviconPath
  * @param? versionInfo
+ * @param? deprecateGwtUi
  */
 {template .Index}
   <!DOCTYPE html>{\n}
@@ -32,6 +33,7 @@
   <script>
     window.CLOSURE_NO_DEPS = true;
     {if $canonicalPath != ''}window.CANONICAL_PATH = '{$canonicalPath}';{/if}
+    {if $deprecateGwtUi}window.DEPRECATE_GWT_UI = true;{/if}
     {if $versionInfo}window.VERSION_INFO = '{$versionInfo}';{/if}
     {if $staticResourcePath != ''}window.STATIC_RESOURCE_PATH = '{$staticResourcePath}';{/if}
   </script>{\n}