[go mode] Return Pass when commenting inside string/comment

Closes #4739

mode/go/go.js

@@ -162,7 +162,7 @@ CodeMirror.defineMode("go", function(config) {
     },
 
     indent: function(state, textAfter) {
-      if (state.tokenize != tokenBase && state.tokenize != null) return 0;
+      if (state.tokenize != tokenBase && state.tokenize != null) return CodeMirror.Pass;
       var ctx = state.context, firstChar = textAfter && textAfter.charAt(0);
       if (ctx.type == "case" && /^(?:case|default)\b/.test(textAfter)) {
         state.context.type = "}";