Polymer: 2.0を構築する方法は？

説明

マスターブランチを構築することは不可能のようです。

再現する手順

git clone https://github.com/Polymer/polymer.git
cd polymer
npm install
bower install
npm run build

推測される結果

エラーなし

実績

> @polymer/[email protected] build /media/Data/polymer
> gulp

[13:58:14] Using gulpfile /media/Data/polymer/gulpfile.js
[13:58:14] Starting 'build-bundled'...
[13:58:14] Starting 'build-steps'...
[13:58:14] 'build-steps' errored after 129 μs
[13:58:14] Error: Task print-size is not configured as a task on gulp.  If this is a submodule, you may need to use require('run-sequence').use(gulp).
    at /media/Data/polymer/node_modules/run-sequence/index.js:20:10
    at Array.forEach (native)
    at verifyTaskSets (/media/Data/polymer/node_modules/run-sequence/index.js:13:11)
    at runSequence (/media/Data/polymer/node_modules/run-sequence/index.js:92:2)
    at Gulp.<anonymous> (/media/Data/polymer/gulpfile.js:262:3)
    at module.exports (/media/Data/polymer/node_modules/orchestrator/lib/runTask.js:34:7)
    at Gulp.Orchestrator._runTask (/media/Data/polymer/node_modules/orchestrator/index.js:273:3)
    at Gulp.Orchestrator._runStep (/media/Data/polymer/node_modules/orchestrator/index.js:214:10)
    at Gulp.Orchestrator.start (/media/Data/polymer/node_modules/orchestrator/index.js:134:8)
    at runNextSet (/media/Data/polymer/node_modules/run-sequence/index.js:86:16)
[13:58:14] 'build-bundled' errored after 2.13 ms
[13:58:14] Error in plugin 'run-sequence(build-steps)'
Message:
    Task print-size is not configured as a task on gulp.  If this is a submodule, you may need to use require('run-sequence').use(gulp).
Stack:
Error: Task print-size is not configured as a task on gulp.  If this is a submodule, you may need to use require('run-sequence').use(gulp).
    at /media/Data/polymer/node_modules/run-sequence/index.js:20:10
    at Array.forEach (native)
    at verifyTaskSets (/media/Data/polymer/node_modules/run-sequence/index.js:13:11)
    at runSequence (/media/Data/polymer/node_modules/run-sequence/index.js:92:2)
    at Gulp.<anonymous> (/media/Data/polymer/gulpfile.js:262:3)
    at module.exports (/media/Data/polymer/node_modules/orchestrator/lib/runTask.js:34:7)
    at Gulp.Orchestrator._runTask (/media/Data/polymer/node_modules/orchestrator/index.js:273:3)
    at Gulp.Orchestrator._runStep (/media/Data/polymer/node_modules/orchestrator/index.js:214:10)
    at Gulp.Orchestrator.start (/media/Data/polymer/node_modules/orchestrator/index.js:134:8)
    at runNextSet (/media/Data/polymer/node_modules/run-sequence/index.js:86:16)

npm ERR! Linux 4.10.0-20-generic
npm ERR! argv "/usr/bin/nodejs" "/usr/bin/npm" "run" "build"
npm ERR! node v7.9.0
npm ERR! npm  v4.2.0
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @polymer/[email protected] build: `gulp`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the @polymer/[email protected] build script 'gulp'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the @polymer/polymer package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     gulp
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs @polymer/polymer
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls @polymer/polymer
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /home/nazar-pc/.npm/_logs/2017-04-25T10_58_14_261Z-debug.log

バージョン

nodejs --version
v7.9.0
npm --version
4.2.0
bower --version
1.8.0
gulp --version                                                  
[14:15:43] CLI version 3.9.1
[14:15:43] Local version 3.9.1