fix wrongly initialized clike-mode top-level context

Author: marijnh

lib/codemirror.js

@@ -880,7 +880,8 @@ var CodeMirror = (function() {
       }
       else if (how == "smart") indentation = mode.indent(state, line.text.slice(curSpaceString.length));
       else if (how == "add") indentation = curSpace + options.indentUnit;
-      else if (how == "subtract") indentation = Math.max(0, curSpace - options.indentUnit);
+      else if (how == "subtract") indentation = curSpace - options.indentUnit;
+      indentation = Math.max(0, indentation);
       var diff = indentation - curSpace;
 
       if (!diff) {

mode/clike/clike.js

@@ -102,7 +102,7 @@ CodeMirror.defineMode("clike", function(config, parserConfig) {
     startState: function(basecolumn) {
       return {
         tokenize: tokenBase,
-        context: new Context((basecolumn || 0) - indentUnit, "top", false),
+        context: new Context((basecolumn || 0) - indentUnit, 0, "top", false),
         indented: 0,
         startOfLine: true
       };