introduce web_components pkg for consolidated polyfills

pkg/shadow_dom/tool/build.sh

-#!/bin/bash
-# Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-# for details. All rights reserved. Use of this source code is governed by a
-# BSD-style license that can be found in the LICENSE file.
-
-# Usage: call directly in the commandline as test/run.sh ensuring that you have
-# both 'dart' and 'content_shell' in your path. Filter tests by passing a
-# pattern as an argument to this script.
-
-# bail on error
-set -e
-
-DIR=$( cd $( dirname "${BASH_SOURCE[0]}" ) && pwd )
-pushd $DIR > /dev/null
-
-POLYMER_REMOTE=https://github.com/Polymer
-POLYMER_DIR=../../../third_party/polymer
-
-NEWLINE=$'\n'
-REVISIONS=""
-for NAME in ShadowDOM observe-js WeakMap platform-dev; do
-  GIT_REMOTE="$POLYMER_REMOTE/$NAME.git"
-  GIT_DIR="$POLYMER_DIR/$NAME"
-  echo "*** Syncing $GIT_DIR from $GIT_REMOTE"
-  if [ -d "$GIT_DIR" ]; then
-    pushd $GIT_DIR > /dev/null
-    git remote set-url origin $GIT_REMOTE
-    git pull
-    popd
-  else
-    git clone $GIT_REMOTE $GIT_DIR
-  fi
-  pushd $GIT_DIR > /dev/null
-  REVISIONS="$REVISIONS $NEWLINE  $NAME is at revision `git rev-parse HEAD`"
-  popd
-done
-
-echo '*** Installing NPM prerequisites'
-npm install
-
-echo '*** Running grunt'
-grunt
-
-echo "*** Saving REVISIONS file"
-echo "$REVISIONS" > ../REVISIONS