got extends back in the language -- use it together with super

lib/coffee_script/CoffeeScript.tmbundle/Syntaxes/CoffeeScript.tmLanguage

@@ -229,7 +229,7 @@
 		</dict>
 		<dict>
 			<key>match</key>
-			<string>\b(super|this)\b</string>
+			<string>\b(super|this|extends)\b</string>
 			<key>name</key>
 			<string>variable.language.cs</string>
 		</dict>

lib/coffee_script/grammar.y

@@ -11,7 +11,7 @@ token BREAK CONTINUE
 token FOR IN WHILE
 token SWITCH WHEN
 token DELETE INSTANCEOF TYPEOF
-token SUPER
+token SUPER EXTENDS
 token NEWLINE
 token COMMENT
 token JS
@@ -29,8 +29,8 @@ prechigh
   right    '-=' '+=' '/=' '*='
   right    DELETE INSTANCEOF TYPEOF
   left     "."
-  right    THROW FOR IN WHILE NEW
-  left     UNLESS IF ELSE
+  right    THROW FOR IN WHILE NEW SUPER
+  left     UNLESS IF ELSE EXTENDS
   left     ":" '||:' '&&:'
   right    RETURN
 preclow
@@ -81,6 +81,7 @@ rule
   | While
   | For
   | Switch
+  | Extends
   | Comment
   ;
 
@@ -254,6 +255,11 @@ rule
   | Super                             { result = val[0] }
   ;
 
+  # Extending an object's prototype.
+  Extends:
+    Value EXTENDS Expression      { result = ExtendsNode.new(val[0], val[2]) }
+  ;
+
   # A generic function invocation.
   Invocation:
     Value "(" ArgList ")"             { result = CallNode.new(val[0], val[2]) }

lib/coffee_script/lexer.rb

@@ -14,7 +14,7 @@ module CoffeeScript
                   "break", "continue",
                   "for", "in", "while",
                   "switch", "when",
-                  "super",
+                  "super", "extends",
                   "delete", "instanceof", "typeof"]
 
     # Token matching regexes.

lib/coffee_script/nodes.rb

@@ -215,6 +215,20 @@ module CoffeeScript
     end
   end
 
+  # Node to extend an object's prototype with an ancestor object.
+  class ExtendsNode < Node
+    attr_reader :sub_object, :super_object
+
+    def initialize(sub_object, super_object)
+      @sub_object, @super_object = sub_object, super_object
+    end
+
+    def compile(o={})
+      "#{@sub_object.compile(o)}.prototype.__proto__ = #{@super_object.compile(o)}"
+    end
+
+  end
+
   # A value, indexed or dotted into, or vanilla.
   class ValueNode < Node
     attr_reader :literal, :properties, :last