[markdown mode] Improve exiting html sub-mode on blank line

Use same logic as that in htmlBlock

Issue codemirror#5451

Author: marijnh

mode/markdown/markdown.js

@@ -126,9 +126,13 @@ CodeMirror.defineMode("markdown", function(cmCfg, modeCfg) {
     // Reset state.indentedCode
     state.indentedCode = false;
     if (state.f == htmlBlock) {
-      var htmlState = state.htmlState;
-      while ('htmlState' in htmlState) htmlState = htmlState.htmlState; // htmlmixed -> xml
-      if (!htmlState || !htmlState.tokenize || !htmlState.tokenize.isInBlock) {
+      var exit = htmlModeMissing
+      if (!exit) {
+        var inner = CodeMirror.innerMode(htmlMode, state.htmlState)
+        exit = inner.mode.name == "xml" && inner.state.tagStart === null &&
+          (!inner.state.context && inner.state.tokenize.isInText)
+      }
+      if (exit) {
         state.f = inlineNormal;
         state.block = blockNormal;
         state.htmlState = null;

mode/xml/xml.js

@@ -154,7 +154,7 @@ CodeMirror.defineMode("xml", function(editorConf, config_) {
   }
 
   function inBlock(style, terminator) {
-    var closure = function(stream, state) {
+    return function(stream, state) {
       while (!stream.eol()) {
         if (stream.match(terminator)) {
           state.tokenize = inText;
@@ -163,9 +163,7 @@ CodeMirror.defineMode("xml", function(editorConf, config_) {
         stream.next();
       }
       return style;
-    };
-    closure.isInBlock = true;
-    return closure;
+    }
   }
 
   function doctype(depth) {