DRY on the version number: it should be in package.json and nowhere else (#4400)

Cakefile

@@ -90,7 +90,11 @@ task 'build:parser', 'rebuild the Jison parser (run build first)', ->
 
 
 task 'build:browser', 'rebuild the merged script for inclusion in the browser', ->
-  code = ''
+  code = """
+  require['../../package.json'] = (function() {
+    return #{fs.readFileSync "./package.json"};
+  })();
+  """
   for name in ['helpers', 'rewriter', 'lexer', 'parser', 'scope', 'nodes', 'sourcemap', 'coffee-script', 'browser']
     code += """
       require['./#{name}'] = (function() {

lib/coffee-script/coffee-script.js

@@ -1,6 +1,6 @@
 // Generated by CoffeeScript 1.12.1
 (function() {
-  var Lexer, SourceMap, base64encode, compile, ext, fn1, formatSourcePosition, fs, getSourceMap, helpers, i, len, lexer, parser, path, ref, sourceMaps, vm, withPrettyErrors,
+  var Lexer, SourceMap, base64encode, compile, ext, fn1, formatSourcePosition, fs, getSourceMap, helpers, i, len, lexer, packageJson, parser, path, ref, sourceMaps, vm, withPrettyErrors,
     hasProp = {}.hasOwnProperty;
 
   fs = require('fs');
@@ -17,7 +17,9 @@
 
   SourceMap = require('./sourcemap');
 
-  exports.VERSION = '1.12.1';
+  packageJson = require('../../package.json');
+
+  exports.VERSION = packageJson.version;
 
   exports.FILE_EXTENSIONS = ['.coffee', '.litcoffee', '.coffee.md'];
 

src/coffee-script.coffee

@@ -10,9 +10,12 @@ path          = require 'path'
 {parser}      = require './parser'
 helpers       = require './helpers'
 SourceMap     = require './sourcemap'
+# Require `package.json`, which is two levels above this file, as this file is
+# evaluated from `lib/coffee-script`.
+packageJson   = require '../../package.json'
 
 # The current CoffeeScript version number.
-exports.VERSION = '1.12.1'
+exports.VERSION = packageJson.version
 
 exports.FILE_EXTENSIONS = ['.coffee', '.litcoffee', '.coffee.md']