"rake metaparser" and "rake minify" now always generate the target files.

Until now, these tasks looked at the file times and generated the target files
only when they were older than the source files. This caused problems when I
mainupulated the lib/metagrammar.* files by hand sometimes, replaced them from
backups after screw-ups, etc.

Rakefile

@@ -3,11 +3,12 @@ require "uri"
 
 version = File.read("VERSION").strip
 
-file "lib/pegjs-runtime-#{version}.min.js" => "lib/runtime.js" do |t|
+desc "Build the minified parser runtime"
+task :minify do
   response = Net::HTTP.post_form(
     URI.parse("http://closure-compiler.appspot.com/compile"),
     {
-      "js_code"           => File.read(t.prerequisites.first),
+      "js_code"           => File.read("lib/runtime.js"),
       "compilation_level" => "SIMPLE_OPTIMIZATIONS",
       "output_format"     => "text",
       "output_info"       => "compiled_code"
@@ -18,15 +19,10 @@ file "lib/pegjs-runtime-#{version}.min.js" => "lib/runtime.js" do |t|
     abort "Error calling Google Closure Compiler API: #{response.message}"
   end
 
-  File.open(t.name, "w") { |f| f.write(response.body) }
+  File.open("lib/pegjs-runtime-#{version}.min.js", "w") { |f| f.write(response.body) }
 end
 
-file "lib/metagrammar.js" => "lib/metagrammar.pegjs" do |t|
+desc "Generate the grammar parser"
+task :metaparser do
   system "bin/pegjs --start-rule grammar PEG.grammarParser lib/metagrammar.pegjs"
 end
-
-desc "Build the minified parser runtime"
-task :minify => "lib/pegjs-runtime-#{version}.min.js"
-
-desc "Generate the grammar parser"
-task :metaparser => "lib/metagrammar.js"