Treat 'debugger' as a pure-statement keyword, not and identifier.

lib/grammar.js

@@ -32,6 +32,8 @@
         return new LiteralNode($1);
       }), o("CONTINUE", function() {
         return new LiteralNode($1);
+      }), o("DEBUGGER", function() {
+        return new LiteralNode($1);
       })
     ],
     Expression: [o("Value"), o("Call"), o("Code"), o("Operation"), o("Assign"), o("If"), o("Try"), o("While"), o("For"), o("Switch"), o("Extends"), o("Class"), o("Existence"), o("Comment")],

lib/lexer.js

@@ -600,7 +600,7 @@
     };
     return Lexer;
   })();
-  JS_KEYWORDS = ["if", "else", "true", "false", "new", "return", "try", "catch", "finally", "throw", "break", "continue", "for", "in", "while", "delete", "instanceof", "typeof", "switch", "super", "extends", "class", "this", "null"];
+  JS_KEYWORDS = ["if", "else", "true", "false", "new", "return", "try", "catch", "finally", "throw", "break", "continue", "for", "in", "while", "delete", "instanceof", "typeof", "switch", "super", "extends", "class", "this", "null", "debugger"];
   COFFEE_ALIASES = ["and", "or", "is", "isnt", "not"];
   COFFEE_KEYWORDS = COFFEE_ALIASES.concat(["then", "unless", "until", "loop", "yes", "no", "on", "off", "of", "by", "where", "when"]);
   RESERVED = ["case", "default", "do", "function", "var", "void", "with", "const", "let", "enum", "export", "import", "native", "__hasProp", "__extends", "__slice"];

lib/nodes.js

@@ -269,7 +269,7 @@
       return this.isStatement() ? this : LiteralNode.__super__.makeReturn.call(this);
     };
     LiteralNode.prototype.isStatement = function() {
-      return this.value === 'break' || this.value === 'continue';
+      return this.value === 'break' || this.value === 'continue' || this.value === 'debugger';
     };
     LiteralNode.prototype.isPureStatement = LiteralNode.prototype.isStatement;
     LiteralNode.prototype.compileNode = function(o) {

src/grammar.coffee

@@ -78,6 +78,7 @@ grammar =
     o "Throw"
     o "BREAK",                                  -> new LiteralNode $1
     o "CONTINUE",                               -> new LiteralNode $1
+    o "DEBUGGER",                               -> new LiteralNode $1
   ]
 
   # All the different types of expressions in our language. The basic unit of

src/lexer.coffee

@@ -492,7 +492,7 @@ JS_KEYWORDS = [
   "for", "in", "while",
   "delete", "instanceof", "typeof",
   "switch", "super", "extends", "class",
-  "this", "null"
+  "this", "null", "debugger"
 ]
 
 # CoffeeScript-only keywords, which we're more relaxed about allowing. They can't

src/nodes.coffee

@@ -249,7 +249,7 @@ exports.LiteralNode = class LiteralNode extends BaseNode
   # Break and continue must be treated as pure statements -- they lose their
   # meaning when wrapped in a closure.
   isStatement: ->
-    @value is 'break' or @value is 'continue'
+    @value is 'break' or @value is 'continue' or @value is 'debugger'
   isPureStatement: LiteralNode::isStatement
 
   compileNode: (o) ->