in order to support CodeMirror mode of 'text/html' we also have to include…

in order to support CodeMirror mode of 'text/html' we also have to include 'htmlmixed.js' as well as 'css.js' from the CodeMirror distro

common/static/js/vendor/CodeMirror/htmlmixed.js

+CodeMirror.defineMode("htmlmixed", function(config) {
+  var htmlMode = CodeMirror.getMode(config, {name: "xml", htmlMode: true});
+  var jsMode = CodeMirror.getMode(config, "javascript");
+  var cssMode = CodeMirror.getMode(config, "css");
+
+  function html(stream, state) {
+    var style = htmlMode.token(stream, state.htmlState);
+    if (style == "tag" && stream.current() == ">" && state.htmlState.context) {
+      if (/^script$/i.test(state.htmlState.context.tagName)) {
+        state.token = javascript;
+        state.localState = jsMode.startState(htmlMode.indent(state.htmlState, ""));
+      }
+      else if (/^style$/i.test(state.htmlState.context.tagName)) {
+        state.token = css;
+        state.localState = cssMode.startState(htmlMode.indent(state.htmlState, ""));
+      }
+    }
+    return style;
+  }
+  function maybeBackup(stream, pat, style) {
+    var cur = stream.current();
+    var close = cur.search(pat), m;
+    if (close > -1) stream.backUp(cur.length - close);
+    else if (m = cur.match(/<\/?$/)) {
+      stream.backUp(cur[0].length);
+      if (!stream.match(pat, false)) stream.match(cur[0]);
+    }
+    return style;
+  }
+  function javascript(stream, state) {
+    if (stream.match(/^<\/\s*script\s*>/i, false)) {
+      state.token = html;
+      state.localState = null;
+      return html(stream, state);
+    }
+    return maybeBackup(stream, /<\/\s*script\s*>/,
+                       jsMode.token(stream, state.localState));
+  }
+  function css(stream, state) {
+    if (stream.match(/^<\/\s*style\s*>/i, false)) {
+      state.token = html;
+      state.localState = null;
+      return html(stream, state);
+    }
+    return maybeBackup(stream, /<\/\s*style\s*>/,
+                       cssMode.token(stream, state.localState));
+  }
+
+  return {
+    startState: function() {
+      var state = htmlMode.startState();
+      return {token: html, localState: null, mode: "html", htmlState: state};
+    },
+
+    copyState: function(state) {
+      if (state.localState)
+        var local = CodeMirror.copyState(state.token == css ? cssMode : jsMode, state.localState);
+      return {token: state.token, localState: local, mode: state.mode,
+              htmlState: CodeMirror.copyState(htmlMode, state.htmlState)};
+    },
+
+    token: function(stream, state) {
+      return state.token(stream, state);
+    },
+
+    indent: function(state, textAfter) {
+      if (state.token == html || /^\s*<\//.test(textAfter))
+        return htmlMode.indent(state.htmlState, textAfter);
+      else if (state.token == javascript)
+        return jsMode.indent(state.localState, textAfter);
+      else
+        return cssMode.indent(state.localState, textAfter);
+    },
+
+    electricChars: "/{}:",
+
+    innerMode: function(state) {
+      var mode = state.token == html ? htmlMode : state.token == javascript ? jsMode : cssMode;
+      return {state: state.localState || state.htmlState, mode: mode};
+    }
+  };
+}, "xml", "javascript", "css");
+
+CodeMirror.defineMIME("text/html", "htmlmixed");