merge lib_chart into graphs bundle

app/assets/javascripts/graphs/graphs_bundle.js

+import Chart from 'vendor/Chart';
 import ContributorsStatGraph from './stat_graph_contributors';
 // export to global scope
+window.Chart = Chart;
 window.ContributorsStatGraph = ContributorsStatGraph;

app/assets/javascripts/lib/chart.js

-/* eslint-disable func-names, space-before-function-paren */
-
-window.Chart = require('vendor/Chart');

app/views/projects/graphs/charts.html.haml

 - @no_container = true
 - page_title "Charts"
 - content_for :page_specific_javascripts do
-  = page_specific_javascript_bundle_tag('lib_chart')
   = page_specific_javascript_bundle_tag('graphs')
 = render "projects/commits/head"

app/views/projects/graphs/show.html.haml

 - @no_container = true
 - page_title "Contributors"
 - content_for :page_specific_javascripts do
-  = page_specific_javascript_bundle_tag('lib_chart')
   = page_specific_javascript_bundle_tag('graphs')
 = render 'projects/commits/head'

app/views/projects/pipelines/charts.html.haml

 - @no_container = true
 - page_title "Charts", "Pipelines"
 - content_for :page_specific_javascripts do
-  = page_specific_javascript_bundle_tag('lib_chart')
   = page_specific_javascript_bundle_tag('graphs')
 = render 'head'

config/webpack.config.js

@@ -40,7 +40,6 @@ var config = {
     snippet:              './snippet/snippet_bundle.js',
     terminal:             './terminal/terminal_bundle.js',
     users:                './users/users_bundle.js',
-    lib_chart:            './lib/chart.js',
     lib_d3:               './lib/d3.js',
     vue_pipelines:        './vue_pipelines_index/index.js',
   },