Remove duplicate pivot:compile.

Guardfile

@@ -1,3 +1,3 @@
 guard :shell do
-  watch(/^src\/.+\.js/) { `rake pivot:compile && rake pivot:docs` }
+  watch(/^src\/.+\.js/) { `rake pivot:docs` }
 end

Rakefile

@@ -17,8 +17,7 @@ require_relative './demo_csv_builder.rb'
 
 namespace :pivot do
   desc "Compiles docs"
-  task :docs do
-    Rake::Task["pivot:compile"].invoke
+  task :docs => :compile do
     system("jsduck ./pivot.js --output ./docs")
     $stdout.puts "Docs have generated"
   end